APPLICATION OF BIOENERGY ASH AS A FERTILIZER FOR CONIFER
SEEDLINGS IN A SUB-BOREAL REFORESTATION SITE IN THE
CENTRAL INTERIOR, BRITISH COLUMBIA
By
Nichola Gilbert
B.Sc. University of Northern British Columbia, 2013

THESIS SUBMITTED IN PARTIAL FULFILLMENT OF
THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF SCIENCE
IN
NATURAL RESOURCES AND ENVIRONMENTAL STUDIES (FORESTRY)

UNIVERSITY OF NORTHERN BRITISH COLUMBIA
August 2018
© Nichola Gilbert, 2018

Abstract
In the Central Interior, British Columbia, bioenergy generated from wood wastes is
increasingly popular. To mitigate the ash surplus, two trials (seedling pot and field)
examined conifer seedlings (lodgepole pine and hybrid spruce) subjected to
treatments comparing two bioenergy ash types (gasifier and boiler), combined with
nitrogen or alone. Two placement techniques, broadcast spread and teabag, plus
two rates of application (2 tonnes ha-1 and 4 tonnes ha-1) were also compared. After
51 weeks, seedling pot results suggested both species benefited from ash with
nitrogen. In the field trial, after 57 weeks, the gasifier ash, which was high in mineral
content compared to the charcoal-filled boiler ash, had increased spruce height,
without nitrogen; this ash also spurred the highest soil pH increase, especially when
broadcast spread. Also, the low dose of ash was preferred. It is likely ash application
can improve reforestation success, providing site conditions and species are
compatible.

ii

Table of Contents
Abstract ............................................................................................................................. ii
Table of Contents ............................................................................................................ iii
List of Figures ................................................................................................................... v
List of Tables ................................................................................................................... vii
Acknowledgements ....................................................................................................... viii

Chapter 1 Introduction ............................................................................................. 1
Background ....................................................................................................................... 4
Forest disturbance and ash ............................................................................................ 4
Wildfire ...................................................................................................................................... 4
Bark beetles .............................................................................................................................. 6
Timber harvesting ..................................................................................................................... 7

Ash fertilization................................................................................................................ 8
Ash composition ........................................................................................................................ 8

Ash application.............................................................................................................. 11
Ash and soil pH ....................................................................................................................... 13
Ash and soil communities ....................................................................................................... 15

Application in forest industry ......................................................................................... 18
Tree growth and forest fertilization .......................................................................................... 18
Application rate determination ................................................................................................. 20
Fertilizer placement ................................................................................................................. 22

Study Objective and Research Questions ................................................................... 23

Chapter 2 Seedling pot trial: Conifer seedlings fertilized with ash and nitrogen
grown for one year .................................................................................................. 27
Introduction ..................................................................................................................... 27
Materials and Methods ................................................................................................... 29
Site description and trial design .................................................................................... 29
Soil collection and preparation ................................................................................................ 31

Ash types and application rates .................................................................................... 33
Teabag and broadcast application methods ................................................................. 37
Seedling potting and treatment placement ................................................................... 38
Seedling vigour assessment ......................................................................................... 43
Stem and needle harvest .............................................................................................. 45
Root harvest and soil sample collection........................................................................ 46
Data analysis ................................................................................................................ 48
Results ............................................................................................................................. 50
Aboveground growth and mass .................................................................................... 50
Belowground growth and mass..................................................................................... 53
Ratios and total biomass............................................................................................... 57
Foliar analysis ............................................................................................................... 60
Soil pH .......................................................................................................................... 66
Vigour assessment ....................................................................................................... 67
Discussion ....................................................................................................................... 69

Chapter 3 Field trial: Conifer seedlings fertilized with bioenergy ash and
nitrogen in SBSwk1 harvest cutblock ................................................................... 76
Introduction ..................................................................................................................... 76
Materials and Methods ................................................................................................... 78
Site description ............................................................................................................. 78
Trial design ................................................................................................................... 80

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Seedling planting and plot set-up.................................................................................. 81
Treatment placement .................................................................................................... 84
Soil collection and characterization............................................................................... 87
Measurements and analyses ........................................................................................ 89
Results ............................................................................................................................. 90
Analysis of control treatments ....................................................................................... 90
Factorial analysis .......................................................................................................... 92
Discussion ....................................................................................................................... 96

Chapter 4 General discussion and final conclusions ....................................... 102
Conclusion .................................................................................................................. 105

References ............................................................................................................. 107
Appendices ............................................................................................................ 114
Appendix A: List of treatments used in both trials ................................................... 114
Appendix B .................................................................................................................... 115
Overview map of Blocks 25 and 26 ............................................................................ 115
Overview map of field trial site in Block 26 ................................................................. 116
Appendix C: Chemical properties of ash types ......................................................... 117
Appendix D: Calculations for ash application rate .................................................... 119
Appendix E: Foliar analysis ......................................................................................... 120
Appendix F: Foliar nutrient interpretative criteria ..................................................... 122
Appendix G: Soil properties ........................................................................................ 123
Seedling pot soils ........................................................................................................ 123
Field site soils ............................................................................................................. 124
Appendix H: Edatopic grid for the SBS wk1 (Willow variant) ................................... 126
Appendix I: Seedling pot trial data .............................................................................. 127
Appendix J: Field trial data .......................................................................................... 129

iv

List of Figures
Figure 1: The mean, maximum and minimum temperature data collected from the weather
station located at the Prince George Airport. ......................................................................... 30
Figure 2: The general area for the soil collection from Aleza Lake Research Forest ................. 32
Figure 3: The flat iron, heated to medium-high heat, was pressed along the seam for 2-3
seconds to seal the teabag closed. ......................................................................................... 38
Figure 4: Examples of the spruce seedling stock (412A PSB) selected for the trial ................... 40
Figure 5: Images showing the insertion of the teabags into the seedling pots. .......................... 42
Figure 6: (a). The seedlings, on-site at the EFL compound. .......................................................... 43
Figure 7: Representative pine samples are shown to give the scale used to assess vigour in
the pine samples. ...................................................................................................................... 44
Figure 8: The representative spruce samples for vigour assessment. ........................................ 45
Figure 9: The pH soil samples were extracted from 3 points (marked by X). .............................. 47
Figure 10: The median shoot mass for the Nitrogen-only and Control (No-Nitrogen, no
treatment) samples compared by species and N addition ................................................... 51
Figure 11: The final median height of the pine and spruce seedlings treated with ash x
nitrogen compared to the Control samples. ........................................................................... 52
Figure 12: The median root mass for the Nitrogen-only and No-Nitrogen (Control, no
treatment) samples compared by species .............................................................................. 53
Figure 13: The final median root collar diameter (RCD) of the pine and spruce seedlings
treated with ash x nitrogen compared to the Control samples. ........................................... 54
Figure 14: The median RCD growth of the pine and spruce seedlings compared by ash
application rate and nitrogen addition. ................................................................................... 56
Figure 15: The median RCD growth of the pine and spruce seedlings compared by placement
(Bc= Broadcast; Tb= Teabag) and nitrogen addition. ............................................................ 57
Figure 16: The median root mass of the pine and spruce seedlings compared by placement
(Bc= Broadcast; Tb= Teabag) and nitrogen addition. ............................................................ 57
Figure 17: The final median HDR of the pine and spruce seedlings compared by ash type and
nitrogen addition. (n = 10) ........................................................................................................ 58
Figure 18: The median total mass of the pine and spruce seedlings compared by placement
method and nitrogen addition .................................................................................................. 59
Figure 19: The median root to shoot (R:S) ratio of the pine and spruce seedlings compared by
placement method and nitrogen addition ............................................................................... 60
Figure 20: The median total boron (mg/kg) of the pine and spruce seedlings compared by ash
type and nitrogen addition. ...................................................................................................... 61
Figure 21: The median total Al (mg/kg) of the pine and spruce seedlings compared by ash
placement (Bc= Broadcast; Tb= Teabag) and nitrogen addition .......................................... 61
Figure 22: The median total K (%) of the pine and spruce seedlings compared by ash
placement (Bc= Broadcast; Tb= Teabag) and nitrogen addition. ......................................... 62
Figure 23: The nitrogen and potassium ratio (N:K) of the pine and spruce seedlings compared
by ash placement (Bc= Broadcast; Tb= Teabag) and nitrogen addition. ............................ 62
Figure 24: The median nitrogen and magnesium ratio (N:Mg) of the pine and spruce seedlings
compared by ash placement (Bc= Broadcast; Tb= Teabag) and nitrogen addition. .......... 63
Figure 25: The median nitrogen and phosphorus ratio (N:P) of the pine and spruce seedlings
compared by ash placement (Bc= Broadcast; Tb= Teabag) and nitrogen addition. .......... 63
Figure 26: The median nitrogen and phosphorus ratio (N:S) of the pine and spruce seedlings
compared by ash placement (Bc= Broadcast; Tb= Teabag) and nitrogen addition. ......... 63
Figure 27: The median nitrogen and sulphur ratio (N:S) of the pine and spruce seedlings
compared by ash placement (Bc= Broadcast; Tb= Teabag) and nitrogen addition. .......... 64
Figure 28: The median total nitrogen of the pine and spruce seedlings compared by ash type
and nitrogen addition. ............................................................................................................... 64
Figure 29: The median soil pH for the pine and spruce seedlings compared by ash type and
nitrogen addition. ...................................................................................................................... 66
Figure 30: The median soil pH for the pine and spruce seedlings compared by ash placement
(Bc= Broadcast; Tb= Teabag) and nitrogen addition. ............................................................ 67

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Figure 31: a) The field trial area bordered a Riparian Reserve, referred to as a Wildlife Tree
Reserve (WTR) in the legend of the complete map in Appendix B. ..................................... 80
Figure 32: A hybrid spruce seedling with an identification tag attached ..................................... 84
Figure 33: A planter demonstrates how the teabag treatment was inserted near a pine seedling
.................................................................................................................................................... 86
Figure 34: An example of how the broadcast treatment was placed. ........................................... 87
Figure 35: The median total height growth of the pine (Pl) and spruce seedlings (Sx) treated
with teabags (Tb-Only) compared to the control (no-ash) seedlings. .................................. 91
Figure 36: The final median height of the pine (Pl) and spruce (Sx) seedlings treated with
nitrogen (N- only) compared to the control (no-ash, no N) seedlings.................................. 92
Figure 37: The total median height growth (cm) of the pine and spruce seedlings treated with
ash x nitrogen compared to Control (Cont; no ash, no N) samples. .................................... 93
Figure 38: The median final height (cm) of the pine and spruce seedlings treated with ash x
nitrogen compared to Control (Cont: no N, with N) samples. ............................................... 94
Figure 39: The final root collar diameter (RCD) of the pine and spruce seedlings treated with
placement x rate compared to the Controls (no ash and Tb-Only). ..................................... 95
Figure 40: The height to diameter ratio (HDR) of the pine and spruce seedlings treated with
placement x rate compared to the Controls (no ash and Tb-Only). ..................................... 95

vi

List of Tables
Table 1: The attributes of the trial design. ....................................................................................... 31
Table 2: Selected chemical properties of the soil used in the seedling pot trial before and after
the perlite was added ................................................................................................................ 33
Table 3: Chemical properties of the UNBC and CPLP ash types used in the seedling pot trial 35
Table 4: Concentrations of trace elements in UNBC gasifier and CPLP boiler ashes relative to
limits within BC Code of Practice for Soil Amendments ....................................................... 36
Table 5: The monthly precipitation, maximum, minimum and mean temperatures for the
summer of 2014, collected from the Prince George Airport (YXS) weather station ........... 41
Table 6: Factorial ANOVA output for the Control samples compared to the Tb-only samples.. 50
Table 7: Factorial ANOVA output for the Control samples compared to the N-only samples ... 50
Table 8: The statistical summary for the ash X nitrogen factorial ANOVA .................................. 51
Table 9: The 5 factors and 10 interactions tested using a factorial ANOVA for the height,
growth and mass variables ...................................................................................................... 52
Table 10: Factorial ANOVA output for the Control samples compared to the N-only samples . 53
Table 11: Summary statistics for the three-factor ANOVA performed for the belowground
variables ..................................................................................................................................... 54
Table 12: The 5 factors and their second order interactions tested using a factorial ANOVA for
the final RCD measurement, RCD growth and root mass. .................................................... 55
Table 13: Summary statistics for the three-factor ANOVA performed for the combined above
and belowground variables.. .................................................................................................... 58
Table 14: The 5 factors, and their second order interactions tested using a factorial ANOVA for
the Root to Shoot ratio (R:S), Height to Diameter (HDR) and the total biomass (g). .......... 59
Table 15: The 5 factors, and their second order interactions tested using a factorial ANOVA for
the mean nutrient percentage for the foliar chemical analysis ............................................ 65
Table 16: The 5 factors, and their second order interactions tested using a factorial ANOVA for
the mean soil pH values. .......................................................................................................... 66
Table 17: The mean vigour grade for the pine and spruce seedlings based on the attributes
listed in Table 1 ......................................................................................................................... 68
Table 18: The 5 factors, and their second order interactions tested using a factorial ANOVA for
the mean vigour grade .............................................................................................................. 68
Table 19: Chemical characterization of the two ash types, UNBC and CPLP, used in the field
trial. ............................................................................................................................................. 85
Table 20: Chemical characterization of the soil type found at the field trial site ......................... 89
Table 21: Factorial ANOVA results for the Control samples compared to the Tb-only .............. 91
Table 22: Factorial ANOVA results for the Control samples compared to the N-only. ............... 91
Table 23: Statistical summary for the three-factor ANOVA performed for all the growth
variables ..................................................................................................................................... 93
Table 24: The 5 factors and their second order interactions tested using a factorial ANOVA for
the final height, total growth, final RCD, total RCD growth and HDR................................... 94

vii

Acknowledgements
I would like to thank the many individuals that supported me through this “stage” of
my life. Whether with their time, patience or moral support, I could not have
accomplished such a feat without them. First, to my supervisors, Drs. Mike
Rutherford and Hugues Massicotte, thank you for your dedication, patience and
valuable input throughout this project. Thank you Linda Tackaberry, who provided
instrumental guidance throughout the whole project, from potting the seedlings to
applying the treatments in the field, she saw the innermost workings of the study. In
the greenhouse, thank you Scott Brown, who provided support wherever needed. I
am grateful for the funding for the project, provided by NSERC and Canfor Pulp
Limited Partnership (acquired by Dr. Mike Rutherford). I would like to thank the many
faculty members who provided invaluable guidance and encouragement. To name a
few: Ché Elkin, thank you for your knowledge and advice for all-things statistics;
Scott Green for your advice and for always being engaged with your students; Lito
Arocena and Paul Sanborn, for teaching me the fundamentals of soils. Thank you to
the PRT Nursery for providing the tree seedlings, thanks to Mike Jull who brokered
the exchange; the laboratory and greenhouse staff that assisted with the project:
Saskia Hart, who provided impeccable quality of laboratory work and eye for detail;
John Orlowsky and Doug Thompson, who gave support for all things greenhouserelated; Erwin Rehl, who measured out the many ash and nitrogen treatments in the
lab, with keen attention to detail; Abby Lewis and Anthony Gilbert, who also provided
help in the greenhouse. Thank you to the Aleza Lake Research Forest staff, who
assisted throughout the field trial: Mike Jull and Colin Chisholm, for providing advice,
energy, labour, for setting aside area and providing spruce (planted by Celtic
Reforestation) and pine seedlings for the field trial. Warren Neuvonen, Anthony
Gilbert and Colin Chisholm for planting the pine seedlings with me; Sam (Pederson)
Gonzalez, Karl Domes, Aimee Coleman, Jenn Kanester and Anna Tobiasz, for
assisting in the plot measurements. Dr. Tina Fraser (Aunty), thank you for your
advice and encouragement. To the external examiner, Stéphane Dubé, thank you for
taking the time to provide your perspective. Thank you to my committee members,
Drs. Lisa Wood and Bill McGill for your insights and valuable support throughout this
entire saga. To my mum, Jeannie Gilbert, thank you for your strength. To my family,
friends, neighbours and doggos, near and far (present and passed), for their support,
words of encouragement and unconditional love, many thanks.

viii

Chapter 1 Introduction
The conversion of wood wastes into biofuels and bioenergy is an ideal way to
offset the use of fossil fuels, or other non-renewable energy sources. However, as
bioenergy gains popularity, particularly in British Columbia (B.C.), there is a need to
address the growing amount of ash produced by this energy sector. Currently, ash
residuals are either being stockpiled or landfilled, which are practices that are
increasingly outdated and discouraged (Emilsson, 2006; Hannam et al., 2017, 2018).
While the current regulatory structure in B.C. does not promote recycling wood
ashes (Hannam et al., 2017, 2018), there is an opportunity to utilize this “waste” ash,
as a fertilizer or soil amendment. Other parts of the world, namely Scandinavian
countries, and only some parts of Canada, have recognized the benefits of ash,
which is especially high in selected plant essential nutrients, such as calcium,
potassium, phosphorus and magnesium. Wood ash residuals have been integrated
into forestry and agriculture as a means to raise soil pH (e.g. as a liming agent) and
to supply some nutrients to plants. This study was initiated to increase our
understanding of ash and attempt to find value in utilizing ash in the forests of the
Central Interior, B.C.
In countries where ash fertilization is implemented, the objectives of the ash
amendment vary from improving soil nutrient deficiencies to replenishing the
exported nutrients harvested with the forest stand. Although high in some plant
nutrients, bioenergy ash lacks nitrogen, an important plant nutrient, and one that is
frequently deficient in the forests of central B.C. To improve the performance of ash
as a fertilizer, nitrogen supplements can be added with the dose of ash (Jacobson,
1

2003). However, ash is more often applied as a liming agent to neutralize acidic soils
(Hannam et al., 2016). Substituting ash for synthetic nutrient input is arguably a
function better served by industrial manmade fertilizers (Wang et al., 2007). On the
other hand, there are a number of arguments for applying ash on forestlands in the
Central Interior of B.C. Aside from diversion from the landfill, ash also acts as a
natural soil conditioner and is ubiquitous to the soils of B.C.
When considering ash for land application as a fertilizer or soil amendment,
there are certain factors that should be considered. First, the contents of the fuels
burned should remain purely plant or wood-derived to avoid any problematic trace
element levels. In the case of wood ash accessible to this sub-boreal region, the
woody biomass burned to generate bioenergy mainly consists of wood wastes
leftover from pulp and lumber milling. Heavy metals, such as cadmium and
chromium, occur naturally in tiny amounts in ash, providing there has been no
contamination of the bioenergy woody feedstock (Carlton et al., 2008). Furthermore
the levels of trace metals (e.g.: Cr, Cd, Pb, Ni, Cu, and Zn), solubility and nutrient
levels of ash can also fluctuate (Hannam, 2016; Jacobson, 2003). The physical
texture and chemical properties of ash can also vary depending on the type of
incineration system used in the bioenergy production, the type of fuels burned, and
the temperature at which they were burned (Augusto et al., 2008; Pitman, 2006).
Other factors to consider when planning a large-scale ash application include the
conditions of the receiving site, such as soil type, vegetation abundance and
proximity to waterways (Hannam et al., 2016).
The history of wildfire on the landscape, and forest health agents such as
bark beetles, are important drivers of B.C. ecosystems, contributing to forest
2

dynamics and the distribution of nutrients, especially in the Central Interior of B.C. In
recent decades the impact of bark beetles, namely the mountain pine beetle (MPB),
coupled with wildfire, has forever altered the province’s and the regions’ forest
ecosystems. Timber harvesting, although an “artificial” disturbance, has long
impacted forests in the Central Interior of B.C. After harvesting is complete, and after
other large-scale forest disturbances, reforestation is undertaken in order to
regenerate forests back to a productive ecosystem. It is at the reforestation stage
where an opportunity of introducing ash residuals back into the forest ecosystem is
presented. Bioenergy ash essentially represents ash that would otherwise be
introduced by wildfire or decaying beetle wood. Considering the fuels burned to
generate bioenergy originate from regional forests, returning clean ash residuals, as
a form of fertilizer or liming agent, back to their origin should be a manageable and
encouraged practice.
Utilizing ash at the reforestation stage has not been widely explored. If the
initial years of a seedling’s life are the most vital, and ash can contribute certain
essential plant nutrients, it seemed fitting to examine the use of ash to fertilize
conifer seedlings grown in a controlled (seedling pots) and a natural (field) setting.
Situated in the Sub-Boreal Spruce (SBS) biogeoclimatic ecological classification
(BEC) zone of the Central Interior of B.C., the trials were carried out in a forestry
context. However, it is expected the outcomes could easily be rendered in other
sectors, such as agriculture or mining and for other applications, such as land
reclamation and rehabilitation.

3

Background
Forest disturbance and ash
Wildfire
For millennia, fire has played a fundamental role in shaping our landscapes
(Bowman et al., 2009) and when man began employing it as a tool, the natural
sequence of fire intervals was forever altered (Agee, 1996). On account of British
Columbia’s wildfire history, ash is pervasive in the province’s soil landscape. Even
so, it is rather foreign to think of fertilization using ash derived from bioenergy
production (AshNet, Natural Resources Canada, 2017). In the Sub-Boreal Spruce
(SBS) BEC zone of the Central Interior, wildfire is a common ecological disturbance
(Steen & Coupé, 1997). The resulting post-fire ash composition can depend largely
on tree species and growing conditions (Pitman, 2006); the amount of ash is a result
of site conditions, such as aspect, topography, soil properties (e.g.: soil moisture),
and climate (Aronsson & Ekelund, 2004; Augusto et al., 2008). In the boreal forest, a
burned upper soil organic layer will yield 0.7 to 2.0% in charcoal (Fritze et al., 1994).
Charcoal, the remnants of fire, is an oxidized form of dense carbon that can
eventually benefit the soil’s structure and water-holding capacity (González-Pérez et
al., 2004). Not only can charcoal withstand biochemical breakdown for a long time, it
can also retain Ca+ and Mg+, essential nutrients for plant growth, through adsorption
(Hart & Luckai, 2013).
Ash is an incredibly variable material, especially ash occurring as a result of
wildfire. The rate and duration of wildfire, as well as the drastic shifts caused by
extreme changes in wind direction, are all aspects that add to the variations of
4

wildfire ash (Raison, 1979). Wildfire ash can be wettable and help to reduce post-fire
erosion and runoff by preventing soil sealing (Larsen et al., 2009). However,
depending on the plant species burned and the conditions of the burn (e.g.:
temperature of combustion), ash can influence the wettability of soil by making it
water repellent (Bodí et al., 2011). Bodí and colleagues (2011) found that soil
wettability was improved when a wettable ash was added, but was decreased when
a water-repellent ash was added to a wettable soil.
These contrasts can be attributed to differences in both site and soil
conditions, not to mention the intensity of the fire (Bowman et al., 2009). Fire
intensity can ultimately determine to what extent the wildfire ash will interact with the
soil, native vegetation and the surviving plants as well. Some of these plant species
have inherent adaptations to fire (e.g.: thicker bark, serotinous cones or resprouting
abilities) that are said to be linked to the repetitive occurrence of fire, or a fire regime
(Keeley et al., 2011; Pausas & Keeley, 2009). If these traits are indeed fire-related
adaptations, it can be assumed that these species are also accustomed to having
ash present in the soil profile. The natural presence and tolerance, or adaptation to,
the presence of naturally-occurring ash makes a strong case for utilizing bi-product
ash to fertilize seedlings after timber harvest. Essentially it would be to substitute the
missing component of what would have been, a natural disturbance. For
comparison, low intensity burns can assist in releasing base cation oxides tied up in
soil organic matter and initiate a change in physicochemical soil traits similar to a
small dose of ash at a rate of 1 tonne ha-1 (Fritze et al., 1994; Levula et al., 2000).

5

Bark beetles
Bark beetles (Coleoptera: Curculionidae, Scolytinae) are native pests to North
America and play an important role in forest stand dynamics. Probably the most
important beetle in recent decades for B.C., the mountain pine beetle (MPB;
Dendroctonus ponderosae) has historically played a major function in shaping this
region’s forests (Taylor & Carroll, 2003). However, with climate change contributing
to the severity and frequency of the outbreaks (Carroll et al., 2003; Taylor & Carroll,
2003), the passing MPB outbreak has undoubtedly left its mark on the province’s
forests. Impacting millions of hectares, British Columbia will undergo a 53-70% loss
of merchantable timber by 2021 (Special Committee on Timber Supply, 2012).
Much like wildfire, the MPB has long been a driver of stand dynamics. As host
trees die, they gradually lose needles, branches and crowns, altering ground and
ladder fuel types, and the subsequent path of fire (Jenkins et al., 2012). However, as
Axelson et al. (2009) found, since fire was suppressed throughout most of the 20th
century, MPB outbreaks in the Southern Interior of B.C. took over for the absent fire
regime. Also, over time, the forest stand, likely originating from a stand-replacing fire,
converted from an even-aged cohort of trees, to an uneven-aged stand due to the
gradual fall-down of beetle-killed pines (Axelson et al., 2009).
Due to the socio-economic and environmental implications of this blow to the
province’s timber supply, recommendations for increasing fiber production were
made by the Special Committee on Timber Supply (SCTS) in 2012. One
recommendation included escalating silvicultural practices, such as fertilization, to
encourage the growth of juvenile stands, namely those aged 15-30, and 30-70 years

6

old. According to Brockley (1996), lodgepole pine stands originating from wildfire,
aged 25-30 years, have the highest potential for volume gain from fertilization. Older
stands that were not thinned, or where fire was prevented from naturally thinning,
are not ideal candidates for fertilization due to the limits to crown growth (Brockley,
1996).
Timber harvesting
Besides wildfire and beetles, timber harvesting is another typical forest
disturbance in the Central Interior of B.C. With bioenergy potentially becoming a
mainstay energy source, the amount of wood debris removed from the harvest site
could become worrisome (Hannam et al., 2017). Retaining adequate amounts of
coarse woody debris (CWD) is vital for providing food and habitat for forest flora and
fauna, for promoting soil stability and carbon storage, all which essentially contribute
to a healthy ecosystem (Harmon et al., 1986; Stevens, 1997). Biomass removal as a
result of timber harvest can have repercussions for the ecosystem, and the extent in
severity and duration can depend on a number of factors associated with site, plant
species and climate (Thiffault et al., 2010). In some Swedish forests, whole-stem
harvesting, the most intensive harvesting practice, can impact site productivity for up
to 15-16 years afterward (Olsson et al., 1996). Moreover, the removal of biomass
can cause soil acidification due to leaching of important base cations (Levula et al.,
2000). Much of a conifer’s nutrient stores are associated with the soil-root interface
so when the forest stand is removed, these plant nutrients are liable to leach away
due to less adsorption occurring at the root surface (Persson & Ahlström, 1990). This
leads to a depletion in soil nutrient levels and can induce soil acidification (Federer et

7

al., 1989; Olsson et al., 1996). The mineralization capacity and organic matter inputs
are also altered after timber harvest, with the severity of these soil conditions
depending largely on the intensity of timber removal (Olsson et al., 1996). This
nutrient shortfall is the challenge faced by forest managers and planners tasked with
reforestation. To offset this imbalance, fertilization at the time of planting could offer
a source of nutrition. However, if considering ash application as an alternative to
synthetic fertilizer, it has been widely suggested that application to seedlings should
be avoided (Augusto et al., 2008). By adding ash as an amendment, the modification
of the seedling’s environment may be too drastic, especially when the seedling has
not had enough time to establish some resilience (Augusto et al., 2008).
Ash fertilization
Ash composition
In general, wood ash is valued for its levels of Ca2+, K+, Mg2+ and P (Hannam,
2016; Pitman, 2006; Pöykiö et al., 2004; Steenari et al., 1999; Vance, 1996).
Calcium, which makes up 10 to 30% of ash (Emilsson, 2006), is a fundamental
nutrient that contributes to the structural integrity of plant cell walls (van den
Driessche, 1991). Calcium deficiency in plants causes an inability to allocate
resources for protecting its root tips from toxic levels of metals, such as aluminum
(Kimmins, 2004), which is another component in ash.
There are many factors that influence the levels of plant macronutrients (K,
Ca, Mg, P and S), micronutrients (i.e. Fe, Mn and Cl), and trace elements in
bioenergy ash. For one, tree species can influence the composition of ash, with
hardwoods yielding ash with higher levels of macronutrients than conifers (Pitman,
8

2006). Bark and foliage yield higher ash content than the inner white wood (Werkelin
et al., 2005). Also the combustion temperature will impact important elements (e.g.:
potassium) and metals (e.g.: aluminum) with 500-900°C being optimal for
macronutrient retention (Pitman, 2006).
The collection zone of the ash (i.e. fly or bottom), also plays a crucial role in
ash composition (Demeyer et al., 2001; Pitman, 2006). Fly ash contains the lighter
particles that gather in the flue of the incinerator and is collected from the
electrostatic precipitators (or bag houses) built into the bioenergy system to mitigate
air pollution (Dahl et al., 2010). Bottom ash (also called grate ash) is the heavier
charred fragments that fall through, and is usually collected from underneath the
incinerator or boiler bed (Dahl et al., 2010). While both ash types differ in texture,
chemistry and nutrient levels, heavy metals are typically higher in fly ash (Dahl et al.,
2010; Pitman, 2006). One of the primary concerns surrounding ash for land
application is the potential for high levels of trace heavy metals, such as As, Cd, Cr,
and Hg. Fly ash, which is the ash prone to higher heavy metal content, can still be a
viable fertilizer, providing these levels are checked before land use (Pöykiö et al.,
2004); Pitman (2006) on the other hand recommended that fly ash be avoided for
land application altogether. This is somewhat contradictory to the guidelines set out
under the Environmental Management Act and the Public Health Act, in the Code of
Practice for Soil Amendments (CoPSA). The CoPSA has only listed criteria for fly
ash, and no guidelines for bottom ash (Government of British Columbia, 2007).
According to a Best Management Practices report released by the Ministry of
Environment (MOE), the application of bottom ash would require a waste discharge
permit issued by the MOE (SYLVIS Environmental, 2008).
9

To avoid issues with trace metals in ash, first and foremost, it is important to
know the origin of the bioenergy feedstock that produced the ash (Karltun et al.,
2008). Low levels of heavy metals occur naturally in wood ash, but contaminants can
be introduced by way of wood containing preservatives, insecticides and other
chemicals (Karltun et al., 2008). Saltwater-laden wood wastes can introduce dioxin
emissions into the atmosphere during incineration (Luthe et al., 1997). Ash produced
from saltwater-contaminated wood wastes, when applied as an amendment, can
induce salt phytotoxicity, potentially disrupting growth in conifers (Staples & Van
Rees, 2001).
When ash is applied in its loose form, the sudden abundance of important
soluble cations (i.e. Ca2+, K+ and Na+) has short-lived benefits, similar to a quickrelease fertilizer, and can induce an abrupt pH change (Jacobson, 2003). Finer,
loose particles of ash are liable to dissipate quicker than those of the ash with a
higher content of char (Hart & Luckai, 2013). Therefore, the stabilization of fine ash
into solidified pellets or granules has been widely incorporated into practice to
counteract this rapid leaching (Jacobson, 2003). Granulated ash not only helps to
regulate the release of important cations, it can also help to stabilize the reactivity of
the ash (Steenari et al., 1999; Jacobson, 2003; Karltun et al., 2008). Processing ash
in this way can also render it less soluble than loose ash (Nieminen et al., 2005),
which can provide a longer supply of nutrients similar to a slow-release fertilizer
(Jacobson, 2003). The extent of the nutritional cation abundance and pH change can
depend largely on the soil properties and application rate (Pitman, 2006).
To help alleviate some of the challenges faced with the handling and largescale distribution of ash, aggregation or granulation of loose ash into a hardened or
10

pelletized form is usually recommended (Pitman, 2006). This pre-application process
can help to minimize fine ash dust that can easily become airborne. This ash
particulate can be a workplace hazard for labourers tasked with manually applying
the ash (SYLVIS, 2008). It is advised to take necessary precautions, such as
wearing appropriate personal protective equipment (i.e. face mask, gloves) to
prevent any adverse effects to breathing and contact with eyes and skin.
Ash application
The earliest research on ash fertilization in forests originated in Finland, from
the 1930s (Emilsson, 2006). In Finland, ash fertilization has been used to balance for
K and P depletion from timber harvesting, which typically occurs on millions of
hectares of drained peatlands (Nieminen et al., 2005). Essentially ash fertilizer has
been used to enhance the tree volume in typically nitrogen-rich, drained and dried
land (Emilsson, 2006). The Danish rationale for applying bioenergy ash has been to
balance the nutrient export caused by timber harvesting (Ingerslev et al., 2011). To
determine the amount of ash needed to compensate for the removal of the forest
stand, Ingerslev et al. (2011) found that the varying elemental levels of the bioenergy
ash would prevent all nutrient levels from being satisfied completely, and at the
same time. Adding supplements for S, K, Fe and Zn has been suggested to improve
the quality of ash as a fertilizer (Ingerslev et al., 2011). In other words, to fully
compensate for the loss of the stand, additional nutrient inputs would be needed,
over and above what the ash can supply.
In Northern Germany, Rumpf et al. (2001) applied a weathered mixture of fly
and bottom ash to a 50 year-old Pinus sylvestris stand. The maximum Ca level in the

11

soil solution occurred after 4 months and elevated K occurred up to a depth of
100cm in the soil. In the upper horizons of the soil, increases were observed in
exchangeable Ca and Mg, as well as the cation exchange capacity, nineteen months
post-application (Rumpf et al, 2001).
Sweden has utilized ash generated from bioenergy production for “vitality and
compensatory” fertilization, a need that arises post-harvest. Since 1998 this practice
was also a means to curb the amount of bioenergy ash being landfilled (Emilsson,
2006). Incorporating ash application into forest practices has been considered a
measure to compensate for the loss of nutrients occurring as a result of timber
harvest, and therefore an “ecological measure” (Emilsson, 2006; p. 30).
The effectiveness of ash can last for upwards of 5 years, which was
documented by Solla-Gullón et al. (2008) in a Pinus radiata stand in northern Spain,
a temperate region. Their fly and bottom ash mixture, which had been incorporated
into the upper soil horizons prior to planting the seedlings, increased growth in the
initial stand establishment stage (Solla-Gullón et al., 2008).
In general, the main objectives for ash application have been to counteract
the post-harvest nutrient slump and soil acidity. However, when considering the
variability between study sites, soils, climate, and ash types, there are challenges in
generalizing the use of ash (Hannam et al., 2017), especially considering the various
BEC zones within B.C. alone. In 2008, the MOE compiled the province’s legislation
regarding land application of residuals into a Best Management Practices guidebook
(SYLVIS, 2008). The guide refers to the CoPSA (or the Soil Amendment Code of
Practice), as well as the Organic Matter Recycling Regulation (OMRR; Government
of British Columbia, 2002). To apply ash residuals on land, they must comply with
12

strict criteria including levels of trace elements, for example arsenic and cadmium,
as well as pH (8.9-13.5) and electrical conductivity (16-50 dS m-1).
Provided that nitrogen is not limiting, ash application can improve soil
conditions for plant growth (Jacobson et al., 2014; Hannam et al., 2018), due in part
to the base cations (i.e.: Ca2+, K+, Mg2+, Na+) readily available for plant roots
(Saarsalmi et al., 2001). Optimal ash fertilization has often been reached with the
addition of a nitrogen supplement (Saarsalmi et al., 2001; Jacobson, 2003; Park et
al., 2005). In northern Finland, a long-term study of ash fertilization in a 60 year-old
Scots pine (Pinus sylvestris) stand found volume was significantly increased by ash
applied with N, compared to just nitrogen or ash alone (Saarsalmi et al., 2006).
Ash and soil pH
The alkaline pH and the buffering capacity of bioenergy ash has made it an
effective agent for neutralizing acidic soils (Augusto et al., 2008). In Canada, wood
ash has been used more often as a liming agent than a fertilizer (Hannam et al.,
2016). On account of the acid-buffering hydroxides present in wood ash, ash can
buffer or neutralize soil acidity (Saarsalmi et al., 2001). The neutralizing capacity of
the ash will greatly depend on the amount of Ca2+, K+, Mg2+, Na+ present in the ash
as hydroxides and oxides (Saarsalmi et al., 2001). Increasing the soil pH of an acidic
soil can improve soil nutrient availability for plants, the optimal range being between
pH 5.5-7 (Brady & Weil, 2007).
The buffering capacity of ash is not only valued in forestry, but also in
agriculture and reclamation (SYLVIS, 2008). The use of ash for liming has been
employed in agricultural sectors in Alberta, B.C., New Brunswick, Nova Scotia, and

13

Quebec, and forestry sectors in B.C. and New Brunswick (Hannam et al., 2016).
Pure ash, or completely combusted green fuels, can have a pH between 9-13 and
the buffering capacity can be the equivalent of 50 to 70% of pure limestone
(Emilsson, 2006). Ash is primarily composed of calcium, in the form of CaCO3, which
is the agent that prompts the liming effects of ash (Augusto et al., 2008; Steenari &
Lindqvist, 1997).
Clearcut harvesting withdraws nutrients contained in the trees that would
otherwise contribute to site’s soil nutrient levels. Depending on the amount of
biomass removal, the input from other organic sources may not compensate for the
loss (Olsson et al., 1996). When living trees are removed, the negative charges
associated with the root surface are reduced, thereby decreasing the cation
exchange capacity (CEC) of the soil (Kimmins, 2004; p.295). This withdrawal of
nutrients can induce an acidic soil environment, the extent dependent on the amount
of harvest removal (Olsson et al., 1996). Soil acidity is an issue due to the potential
for the mobilization of aluminum (McHale et al., 2007), which has been a concern in
northern Europe, since the 1960s (Emilsson, 2006). This is because aluminum is
liable to leach into freshwater and groundwater, harming stream quality and
subsequently, fish populations (Emilsson, 2006; McHale et al., 2007). Limiting the
mobilization of Al is another advantage to neutralizing an acidic soil by channeling
the liming capacity of bioenergy ash.

14

Ash and soil communities
Macro and mesofauna
The input of ash is liable to disrupt biological processes that drive the food
and habitat cycles of organisms that reside in soil. Qin et al. (2017) documented
mesofauna, namely collembola, being negatively impacted by ash applied at high
application rates (i.e. 17 tonnes ha-1). In those cases, the ash effect was essentially
temporary, but depending on soil type, osmotic stress could be the main factor in this
mesofauna decline, as opposed to the rise in pH (Qin et al., 2017).
Conversely in Central Ontario, Gorgolewski et al. (2016) set up a study in a
mixed-deciduous (sugar maple, and American beech) stand to determine the impact
of ash application on the abundance of Eastern Red-backed Salamander. Native to
the region’s forests, the salamanders seemed to benefit from the increased soil pH
and the moisture retention caused by the fly ash application, compared to the bottom
ash treated areas and the controls (Gorgolewski et al., 2016). Ash is considered
hydrophilic and can retain water through capillary action (Etiégni & Campbell, 1991,
as cited in Pitman, 2006), which can be an advantageous property of soils that host
many diverse forest mesofauna.
Microfauna and microflora
Soil microbes can either proliferate or dwindle, depending on the rate of ash
applied (Bääth et al., 1995). Perkiömäki and Fritze (2002) found wood ash (3 tonnes
ha-1) increased microbial activity and soil respiration, which can be attributed to the
decrease in soil acidity (Fritze et al., 1994). Yet Bååth and colleagues (1995) found
an application rate of 2.5 tonnes ha-1 decreased microbial activity, with the fungi
15

impacted more than the bacteria. Nevertheless, depending on the concentration of
base cations in the ash, the rise in microbial activity could be short-lived (Perkiömäki
& Fritze, 2002; Zimmermann & Frey, 2002).
If applied without adhering to best management practices, damage can occur
to foliage, fine roots (Persson & Ahlström, 1990), and also mycorrhizae (Erland &
Söderström, 1991). Regarding mycorrhizae, the abrupt pH change associated with
ash fertilization can hinder the function of those associated with some berry shrub
species (Moberg & Tidström, 1985 as cited in Levula et al., 2000). Even so,
mycorrhizal colonization of hardened ash has been reported (Mahmood et al., 2002;
Hagerberg et al., 2005). In Hagerberg et al.’s (2005) study, the presence of Ca in
Piloderma sp., a prevalent fungi in coniferous and hardwood forests, extended from
where the ash was applied to farther extremities of its fungal structure. This
translocation of Ca in fact exceeded that of P and K (Hagerberg et al., 2005). The
observation could be attributed to the proclivity of ectomycorrhizae to reinforce its
hyphae with a calcium sheath, possibly in an effort to prevent desiccation (Arocena
et al., 2001). Aside from Ca, Mahmood et al. (2002) emphasized the importance of
Piloderma’s role in the mobilization of P from ash.
Ash and ground vegetation
When applying ash via broadcast application, in the absence of mechanical
site preparation, ash is likely to be intercepted by ground vegetation, such as
mosses, forbs, and shrubs. Depending on the rate of application, ash can interact
immediately with the ground vegetation. In a Scots pine fertilization trial study
performed in Lithuania, the moss Pleurozium schreberi, was impacted up to 2 years

16

after ash and nitrogen application at a rate of 5 tonnes ha-1 (Ozolinčius et al., 2007).
In the B.C.’s Central Interior, certain ash types mixed with urea were detrimental to
some forbs and grasses, but beneficial for some shrubs and bryophytes (Hart, B.Sc.
Undergraduate Thesis, University of Northern B.C., 2017). To minimize any
unfavorable effects from ash, it is usually recommended to stabilize or harden the
ash prior to application (Jacobson, 2003; Hannam et al., 2018). Another
recommendation would be to consider the timing and seasonality of the ash
application (Hannam et al., 2018). For example, ash could be applied in parallel with
mechanical site preparation prior to reforestation, or during thinning and other
silviculture operations, to minimize the amount of entries into the site (Hannam et al.,
2018)
In Central Sweden, Norström et al. (2012) studied wood ash application of a
50-80 year old Norway spruce (Picea abies) and Scots pine (Pinus sylvestris L.)
stand treated with 6 tonnes ha-1 (with 50% moisture content equating to 3 tonnes
ha1). The contents of bilberries (Vaccinium myrtillus L.) were examined two years
prior and post-application of self-hardened ash and found the levels of trace metals
were unchanged (Norström et al., 2012). An increase in K in the soil solution was
noted, which is a prevalent observation in many ash fertilization studies.
Interestingly, boron was the only elemental level significantly higher than that of the
control berries (Norström et al., 2012).
In Central Finland, after the 1986 Chernobyl accident, radiation levels in the
berries and fungi were closely studied. Because of evidence showing the potential of
radioactive caesium (Cs), or radiocaesium, entering the food chain, Levula et al.
(2000) set up trials in 100-year-old Scots pine stands. They compared ash
17

fertilization and prescribed burning and found both practices decreased the Cs levels
in the berries several years after application (Levula et al., 2000). These findings
could have implications for areas suitable for reforestation where radiation fallout is
an issue.
Application in forest industry
Tree growth and forest fertilization
The success of forest fertilization will depend on many factors, such as site
characteristics, fertilizer formula, the seedling stock, the application rate and the
placement of the fertilizer (van den Driessche, 1991; Rose & Ketchum, 2002).
Typically, the objective of fertilization in forestry is to improve a nutrient deficiency,
either caused by poor land management practices or just a nutrient deficiency typical
of most forest soils (Smith et al., 1997). For large-scale soil nutrient deficiencies,
fertilization is usually considered too expensive, and usually requires more than just
one application for it to be worthwhile (Smith et al., 1997). Repeated applications of
fertilizers, complemented by another treatment such as pre-commercial thinning or
brushing, can help increase volume, particularly in lodgepole pine (Lindgren et al.,
2007). Ideally, to regenerate a site successfully, conditions and growing space
should favour the preferred crop species, rather than the adjacent competitive
species (Smith et al., 1997). Limiting competitive vegetation for the seedling could
help alleviate pressures on soil moisture supply, one of the most important site
factors for predicting fertilization success. If soil moisture is limited, and depending
on the formula of fertilizer, excess nutrients can surround the root tips, causing
saline conditions in the soil environment. This increase in salinity could lead to
18

irreparable damage to the root system, essentially limiting the growth of the
seedlings (Jacobs et al., 2004; Rose & Ketchum, 2002). Comparably, ash
application can be predisposed to high salinity concentrations, even in established
stands (SYLVIS, 2008).
Fertilization studies from B.C. Central Interior pine forests have documented
nutrient deficiencies, with the most renowned likely being nitrogen (Brockley, 1990,
1996). This shortage is said to be attributed to the volatilization of nitrogen occurring
as a result of a frequent fire regime, which were typical of pine forests in this region
(Brockley, 1990). Deficiency of nitrogen in plants can impact the plant’s ability to
process chlorophyll, leading to the yellowing of foliage, and eventual mortality
(Kimmins, 2004). Nitrogen fertilization is a common practice in some regions where
moisture is not limiting, like in the Pacific Northwest for instance (Smith et al., 1997).
However, the application of nitrogen can be futile if soil moisture and phosphorous
levels are inadequate (Smith et al, 1997). Typical silviculture fertilizers include
diammonium phosphate (at a rate of 56kg P·ha-1) and ammonium nitrate (at a rate of
225kg N·ha-1;Stovall et al., 2012). As Brockley (2012) pointed out, when assessing
the needs for fertilization, ratios of P, K and Mg with N (i.e. N:P, N:K, N:Mg) are more
important than the absolute values of the nutrient alone.
Aside from nitrogen, deficiencies in sulphur, as well as boron, have been
documented in older pine stands in the B.C. Interior (Brockley, 1996, 1990; Sanborn
et al., 2005). Sanborn et al. (2005) found in a single application of fertilizer (100kg
S·ha-1 + 400kg N·ha-1), elemental S (S0) provided a long-term sustained S level at
an S-deficient site for up to 12 years. Nitrogen and sulphur are closely linked and
both rely on soil microbial activity to become available for plant uptake (Kimmins,
19

2004). The balance of the two is important because they are both associated with
certain plant processes and therefore when the levels of both are ideal (i.e. N:S),
both are optimized (Brady & Weil, 2007).
Application rate determination
Ash composition and properties of the receiving site are important factors to
consider when determining an appropriate ash application rate. Essentially the
maximum rate of application is constrained by the levels of 11 trace elements
(arsenic, cadmium, chromium, cobalt, copper, mercury, molybdenum, nickel, lead,
selenium and zinc), which must be verified and within acceptable ranges when
considering ash for land application (Hannam et al., 2016). Other factors sometimes
considered are ash pH, moisture content, and potential contaminants, most notably
dioxins and furans (Hannam et al., 2016). The level of indicator nutrients, such as
phosphorous or potassium, is another tool for determining an application rate for ash
(Pitman, 2006; SYLVIS, 2008; Hannam et al., 2016). For example, in Denmark, 30kg
per hectare of phosphorus contained in the ash is a typical guideline (Pitman, 2006).
On the basis of the receiving site, to assess the need for fertilization of any
kind, foliar analysis is a useful tool for determining what nutrients are required,
potential reasons for nutrient deficiencies, and which stands will respond best to
treatment (Brockley, 1996, 2001). While this technique typically applies to
established conifer stands, this method does not take into consideration the needs of
seedlings. Using ash to fertilize seedlings has not typically been encouraged
(Augusto et al., 2008). Nevertheless, when considering ash for fertilization, as
previously mentioned, the literature on the effects of ash does not always agree. For

20

instance, Bååth et al. (1995) found an application rate of 2.5 tonnes ha-1 decreased
microbial activity, with the fungi more impacted than the bacteria. Meanwhile a
slightly higher rate of 3 tonnes ha-1 initiated an increase in microbes and soil
respiration, as reported by Perkiömäki and Fritze (2002). Differing site conditions
and ash type may have contributed to the divergent responses.
In Finland, the allowable rate of ash application for the drained and nitrogenrich peatlands is between 3-5 tonnes ha-1 (Emilsson, 2006). In Southern Finland,
Saarsalmi et al. (2001) studied a loose ash application of 3 tonnes ha-1 in a young,
5-6 year-old, Scots pine and Norway spruce stand. They found the neutralizing and
fertilizing properties of the ash lingered up to 16 years after application (Saarsalmi et
al., 2001). Increases in cation exchange capacity (CEC), pH and base saturation
induced by ash also resonated 16 years later, with levels of exchangeable Ca and
Mg still prevalent in the humus and mineral layers (Saarsalmi et al., 2001).
Saarsalmi et al. (2001) suggested that 4 tonnes ha-1 is the optimum rate of
application. Pitman (2006) explained that application rates exceeding 10 tonnes ha-1
tend to cause excessive dieback. On the other hand, Vance (1996) insisted that a
single application of ash at a rate of 10 tonnes ha-1 could replace most of the
nutrients that were exported through harvest.
In Canada, due to the fact fertilization using ash is in its infancy, there are no
maximum limits set for application rate for forests (Hannam et al., 2018). Instead the
limits set are by agricultural standards and far exceed even the highest
recommended rates in Europe (Hannam et al., 2018). For instance, in Alberta, the
allowable ash dosage on agricultural soils is 45 Mg ha-1 (cumulative) compared to a

21

maximum of 7 Mg ha-1 allowed for the life of a stand rotation in Lithuania (Hannam et
al., 2018).
Fertilizer placement
Generally, the most efficient way of dispersing a large quantity of ash is by
mechanical ground spreader, or aerially, by helicopter (Emilsson, 2006). Ground
application, likely the most cost-effective (Emilsson, 2006), is not necessarily ideal in
a forest due to variable and uneven terrain; also the spacing between the trees may
not accommodate a machine. While these application methods are suitable for
established stands, where seedlings are involved, the method of application should
limit disturbance to the seedling. The stage at which fertilization should take place
has been debated, whether prior to planting or when vegetation has already been
established (Emilsson, 2006; Hannam et al., 2018). Moreover, there have been
fertilization delivery techniques currently used in forestry that have not yet been
explored for ash.
Integrating ash application into a reforestation strategy will need consideration
of the method of application, and the terrain of the area of application. In forestry,
there is a method of fertilization that utilizes teabags packed with pellets of fertilizer
(Reforestation Technologies Inc.). These fertilizer teabags can either be placed
within the same hole as the seedling or adjacent to it, usually on the “uphill” side in a
different hole. For a seedling trial in Saskatchewan, teabags with 20-6-12-6 (N-P-KS) controlled-release fertilizer were placed in the same hole as the seedlings, 5-7cm
away from the root plug (Hangs et al., 2003). This method required the treeplanter to
dig a hole large enough to insert the teabag at the bottom, cover it with soil, and then

22

inserting the seedling over top of the teabag, and closing the hole. Using the teabag
method, Fan et al. (2002) used a slightly different method whereby the fertilizer
teabag was placed in a separate hole on the uphill side of the microsite, 8cm away
from the seedling, at a depth of 15cm. Both of these localized fertilization methods
should be considered on sites where competitive species may be an issue. In
comparison, a broadcast application of fertilizer could contribute to the success of
non-target species, compromising the success of the conifer seedlings (Staples et
al., 1999). Considering ash is typically spread by broadcast method, it may not be an
ideal technique for reforestation sites where competitive species are abundant.

Study Objective and Research Questions
The main objective for the two study trials (the seedling pot study and field
trial) was to determine which factors were important when utilizing ash sourced from
local bioenergy generators to fertilize lodgepole pine and hybrid spruce seedlings in
the sub-boreal zone of B.C. To determine this, seedlings were grown in pots outside
a greenhouse and the same two species were also planted in a natural field scenario
(i.e. in a harvested cutblock). Both sets of seedlings were subjected to site
conditions of British Columbia’s Central Interior Sub-Boreal Spruce (SBS)
biogeoclimatic zone. Monitored for the initial few growing seasons, the two study
trials differed in detail, length of growing time, and number of measurable
parameters. After one growing season and one winter, the seedling pot trial allowed
for in-depth analysis, owing to the deconstruction of the seedlings at the end of the
study period. By separating the stem with needles, root system, and soil samples,
we were able to collect data for the root and shoot masses, foliar chemistry, as well

23

as soil analyses. The field trial lasted for two growing seasons and both trials
allowed for height and diameter measurements and were designed to examine the
influence of these five main factors:
1- tree species
2- ash type
3- ash placement method
4- rate of application
5- nitrogen addition
To address each factor, the research objectives were framed into three questions:
1- Does the species of seedling influence the seedling’s growth response to
bioenergy ash application in conifers planted in the SBSwk1 BEC zone?
Two seedling species used in the study were chosen based on
recommendations from the Aleza Lake Research Forest resident forester (M. Jull,
RPF) and the Ministry (Steen & Coupé, 1997). The first, Pinus contorta (var.
latifolia), or lodgepole pine (shorthand, Pl), was designated a preferred species for
the SBS zone in this region of the Central Interior. The second species, Picea glauca
x engelmannii, or hybrid spruce (Sx), also a preferred species for the Willow (wk1)
variant of the SBS (Steen & Coupé, 1997), was selected as a species to contrast the
pioneering pine.
Both species were planted in soils originating from a SBSwk1 site and
fertilized with different combinations of ash and nitrogen; height and diameter growth
were measured, after one growing season and one winter, and in the field, after
almost a whole year (51 weeks). In the seedling pot trial, seedling growth (height and
root collar diameter), root and shoot masses, nutrient levels in the foliage, soil pH
24

and a visual vigour assessment were recorded; soil pH was also taken in the field
trial. It was hypothesized that the ash-induced growth response would depend
significantly on the tree species, given the conditions of the pot study and the field.
2- Does the ash type influence seedling growth and did nitrogen addition
enhance the growth response?
We compared two ashes differing in bioenergy system of origin, but the
woody fuels, or bioenergy feedstock, for both were comparable in composition. The
ashes were sourced from a gasifier plant (UNBC) and a boiler system (CPLP,
described later) and due to differing efficiencies of each combustion system, the
ashes contrasted greatly in physical and chemical properties, including moisture
content. The finer-textured UNBC ash (mainly mineral matter), with very little
moisture, was predicted to have an immediate short-term effect compared to the
CPLP ash (relatively high in charcoal), which consisted of larger, coarser fragments.
In substituting fertilizer for ash, the benefits of mixing in a nitrogen supplement
to make up for the deficiency in ash have been well documented in the literature. It
was hypothesized seedling growth would be significantly increased by ash
application coupled with a nitrogen supplement. Height and diameter growth, root
and shoot mass, as well as foliage chemistry were measurements taken to analyze
whether adding ash with nitrogen improved the suitability of ash as a fertilizer by
increasing seedling growth. Analysis of the soil pH and the seedling foliage assisted
in determining whether ash type also influenced seedling growth.
3- Does the method of ash application and the rate of application impact the
growth response of the conifer seedling?

25

After establishing whether ash with or without nitrogen initiated a growth
response, the method of distributing ash and the rate at which it was applied were
the next factors examined. The first of the two placement techniques was the
broadcast (Bc) method, whereby the ash was spread evenly over the ground around
the seedling basal area. The second type of ash delivery was adopted from a
technique already employed in forestry, and involved placing ash in a sealed filter
pouch, or teabag (Tb). The ash-filled teabag was then placed in an adjacent hole to
the planted seedling, buried in the soil. It was hypothesized the placement or
delivery mode of ash would have a significant influence on seedling growth. To
determine whether the Bc and Tb placements influenced growth, the seedling stem
height and diameter were measured in both trials. In the extensive seedling pot trial,
in addition to the foliar nutrients and soil pH, the above and belowground growth and
masses were also recorded.
Contrasting application rates to test in the study were determined by first
researching allowable application limits set by local and provincial legislation, and
also countries with similar temperate climates. The capacity of the teabag and the
surface area of the seedling pots were also factors in the decision. In consideration
of the phosphorus content contained in the UNBC and the CPLP ash, the rates
within the allowable range were 3 and 5 tonnes ha-1 respectively. By compiling these
recommendations, the high rate used in the study was 4 tonnes ha-1 and a halved
dose was the low rate, at 2 tonnes ha-1. The analyses of the height and diameter, as
well as foliar chemical analysis, assisted in determining whether the rate of
application was an important factor for seedling growth initiated by ash fertilization.

26

Chapter 2 Seedling pot trial: Conifer seedlings fertilized with ash
and nitrogen grown for one year
Introduction
Addressing the ash residuals generated by the bioenergy industry is a
necessary step to improving the sustainability of this form of renewable energy.
Currently, most bioenergy ash is landfilled in B.C., but considering its potential
applications in forestry, exploring the value-added benefits of ash should be
encouraged. Bioenergy ash produced through the combustion of wood wastes from
paper mills has the potential for use as a liming material and as a dilute fertilizer
(Naylor & Schmidt, 1989). A source of several macro- and micronutrients, ash could
provide a valuable boost to conifer seedlings, which can be important during the
initial establishment stage. Although ash application of seedlings has not been well
explored, introducing ash into the reforestation stage could be a novel way of
utilizing waste ash.
Bioenergy technologies, the origin site of the woody feedstocks used for
bioenergy production, and post incineration handling of the ash are just some of the
factors that add to the variation of ash types (Hope et al., 2017). The utilization of
ash as a forest fertilizer requires a certain degree of handling, which adds to the
challenges of applying it on a large scale. It is especially more complex in a forestry
scenario compared to an agricultural one (Hannam et al., 2017), considering the
constraint of access and terrain in a forest, compared to a farm field. Ash applied to
agricultural fields is easily incorporated into the upper layer of soil, which is not
always practical in forestry. Despite the differences, both agriculture and forestry

27

scenarios must deal with the dust and particulate that is generated by ash
application. This can pose occupational hazards to workers and can also make it
difficult to apply ash at the target application rates. Off-site receptors may be
impacted when ash dust moves into unintended areas. In consideration of these
issues, two methods of ash delivery to young conifer seedlings were considered in
this trial. The broadcast (Bc) method can be labour-intensive and the exposure to the
ash dust can be excessive, when applying at a large scale. To contrast this method,
a more localized technique that uses a teabag to contain the ash was tested. A
method of fertilization already employed in forestry, this teabag delivery method
essentially replicates a method that has been successfully employed in reforestation
strategies throughout B.C. It is inserted alongside the conifer seedling as it is being
planted by the treeplanter. The teabag, usually containing slow-release fertilizer, is
placed either inside the same hole as the seedling, or an adjacent one. By
substituting the fertilizer in the teabag with ash, we were able to explore a fertilization
method already in practice, which also minimizes the need for extra training of
treeplanters.
The seedling pot trial was initiated to determine if ash applied in teabags
would have benefits over non-amended controls or surface-applied ash. A pot study
offered more experimental control over the parallel field trial installed at a
reforestation site, described later in this thesis. Although the environmental
conditions of the seedlings were somewhat controlled in the pot study, the seedlings
were placed outdoors and therefore, were subjected to the natural weather
conditions of the seasons. After 357 days, or 51 weeks, deconstructing samples (i.e.:
biomass harvest and soil sampling) allowed for detailed chemical analyses, not
28

necessarily allowable in a field trial site intended for reforestation. Nonetheless, by
breaking down the seedlings into foliage and root system, inferences on the uptake
and dispersal of the ash within the specimen could be made. In an attempt to learn
more about ash behavior, chemical analysis of the soil allowed for a deeper
examination of the changes occurring in the soil substrate, as a result of ash
additions.
Specifically, the main objective of this seedling pot trial was to determine
which factors, whether ash type, method of application (broadcast surface spread or
teabag), rate of application and nitrogen addition, were main drivers of seedling
growth, or nutrient status of the seedling. The two types of ash chosen for our trials
originated from different bioenergy systems. The fine-textured gasifier ash was
compared with a high carbon (mostly charcoal) ash generated from the boiler of a
local pulp mill. It was hypothesized that the low carbon ash would be better suited for
land application due to its greater mineral content and liming potential. Due to the
fact nitrogen combined with ash has been known to improve the impact of ash
application, it was anticipated that nitrogen-treated seedlings would achieve the
greatest height and diameter growth, compared to seedlings not treated with
nitrogen.

Materials and Methods
Site description and trial design
Located in Prince George, British Columbia, on the campus of the University
of Northern B.C., the I.K. Barber Enhanced Forestry Laboratory (EFL) was the site
for the seedling pot trial. Ninety-five lodgepole pine seedlings and 95 hybrid spruce
29

seedlings with soil modified with ash and/or nitrogen were grown in pots outside in
the fenced compound at the EFL, situated on the north aspect of the compound.
From May 2014 to May 2015, the seedlings were observed for almost a full year
(357 days). The weather data for the time period of this trial is plotted in Figure 1.

Figure 1: The mean, maximum and minimum temperature data collected from the weather station
located at the Prince George Airport (YXS; 53°53'03" N:122°40'39" W), elevation 691m (Government
of Canada, 2015).

An outline of the trial design is given in Table 1, which lists the factors (i.e.:
tree species, method of ash application, ash type, and rate of application) and the
associated codes for each level within the factor. A second set of samples was
treated with nitrogen, the fifth factor. A total of 19 treatments were replicated 5 times,
totaling 95 seedling samples for each species (for full list of treatments, see
Appendix A). The first set of measurements took place from May 21st to May 23rd,
2014 (i.e. when the treatments were put in place) and the final measurements were
taken after one growing season and one winter, on May 6th, 2015.

30

Table 1: The attributes of the trial design, with all levels for each factor associated with the treatments
and the corresponding code (in parentheses). For a complete list of treatments, refer to Appendix A.

Attributes
Species

# of states
2

Details
1- Pinus contorta var. latifolia (Pli)
2- Picea engelmannii x glauca (Sx)

Treatment
Ash types

2

1- Gasifier (UNBC)
2- Boiler (CPLP)
1- Broadcast (Bc)
2- Teabag (Tb)
-1
1- High, 4 tonnes ha (H)
-1
2- Low, 2 tonnes ha (L)
With or without
1- Control (Cont)
2- No ash; with nitrogen (N-Only)
3- No ash; with teabags (Tb- Only)

Ash placement

2

Rate of application

2

Nitrogen
Controls

2
3

Seedlings/replicate
Total number of seedlings planted
Growth recordings

5
190
2

Pli 95, Sx 95
4 and 51 weeks

Soil collection and preparation
Located 60 km east of Prince George B.C, the soil for the seedling pot trial
was collected at the Aleza Lake Research Forest (ALRF; 54°07′ N, 122°04′ W), on
November 2nd, 2013. Just off the West Branch Road of the research forest (Figure
2), on a harvested cutblock (called Block 25), a total of 20 buckets (capacity 18-19L)
were filled with the silt loam (the upper 20 cm of mineral soil was collected; forest
floor was not included). The soil collection site was chosen based on its proximity to
the field trial, located in Block 26 (see Appendix B for Overview map). The buckets of
soil were placed in an unheated 15m x 15m storage shed located at the EFL, and
were stored in mostly frozen conditions for the winter.

31

Figure 2: The general area for the soil collection from Aleza Lake Research Forest is indicated by a
star symbol. (Map source: http://alrf.unbc.ca/wp-content/documents/maps/Exhibit-E-ManagementUnits-Tabloid.pdf)

Prior to potting the seedlings, the frozen soil was prepared for the pots by
mixing it all together to reach a homogenous substrate. On March 17th, 2014, the
buckets of soil were moved from the EFL storage garage into the greenhouse cooler
(4°C) to allow it to gradually thaw. Once thawed and partially air-dried, the substrate
was passed through a 4mm sieve to remove large debris and coarse fragments,
such as rocks, gravel, bark and root wads. The soil from all the buckets was then
placed on a large plastic sheet and, was well mixed, using a shovel. To reduce the
risk of compaction and settlement of the soil (when potted), perlite, a white,
irregularly-shaped, “popped” volcanic material, was added upon the advice of the
greenhouse curators. Added at a ratio of 4:1 (soil: perlite, by volume), the porous
nature of this all-natural inert product vastly improved the drainage of the potted soil.
Four composite samples (each made up of 10 subsamples) of soil without perlite
and four composite samples of perlite-soil mix (also consolidated from 10
32

subsamples) were collected, air-dried, and sent for analysis to the B.C. Ministry of
Environment in Victoria, B.C (for partial description, see Table 2; full analysis in
Appendix F). Overall the two soils were similar with the exception of the inorganic C
level, which was higher in the soil-perlite mix. Soil moisture content was determined
by oven-drying (OD) 5 samples of each soil type, at 105°C for 48 hours; the silt loam
was 8.8% (g H2O 100g-1 OD soil) moisture at the time of experimental set up.
Table 2: Selected chemical properties of the soil used in the seedling pot trial before and after the
perlite was added (n= 4). Each set of values represents a mean (standard deviation in parentheses).
More complete characterizations are given in Appendix G. (n = 4)
No perlite

With perlite

Sand (%)

13.9 (1.24)

14.9 (0.02)

Silt (%)

69.0 (0.75)

68.6 (1.24)

Clay (%)

17.1 (0.64)

16.4 (1.23)

pH (1:1, mL H2O, g solid)

4.96 (0.005)

4.69 (0.005)

CEC (cmol /kg)

13.9 (0.361)

13.7 (0.211)

Available P (mg/kg)

125.3 (9.806)

124.2 (2.851)

Inorganic C (%)

< 0.07 (na)

0.2 (0.10)

Total C (%)

3.4 (0.15)

3.2 (0.05)

Total N (%)

0.181 (0.006)

0.170 (0.004)

Total S (%)

0.023 (0.002)

0.022 (0.004)

B (mg/kg)

5.5 (0.29)

4.7 (0.20)

Ca (%)

0.600 (0.004)

0.582 (0.010)

K (%)

0.267 (0.007)

0.249 (0.010)

Mg (%)

0.572 (0.007)

0.571 (0.009)

+

Ash types and application rates
The two ashes chosen for the trial differed in bioenergy system of origin and
also demonstrate the physical and chemical variations that exist between ash by-

33

products (for brief overview, see Table 3). The UNBC ash originated from the
Nexterra Bioenergy Plant (4.4 MW updraft gasifier) located on the Prince George
campus of the University of Northern B.C. (UNBC). A mixture of mainly bottom ash
with a fly ash component, the ash was produced from waste wood (hog fuel)
generated from local lumber milling operations. The UNBC ash was sourced from
the collection bin of the gasification system on July 13th, 2012. High in pH, the UNBC
ash had low carbon and moisture content compared to the second ash, which was
produced from the milling residues of a pulp mill. The full description of the UNBC
ash is given in Appendix C.
The Canfor Pulp Limited Partnership (CPLP) supplied the second ash type,
which originated from the collection bin of a boiler bioenergy production system
located in the PG Pulp mill in Prince George B.C. Referred to as the CPLP or Canfor
ash, it was collected from the facility on April 27th, 2012 (ash used in this study) and
on January 10, 2013 (ash used in field study). The Canfor ash was primarily
composed of bottom ash and contained more charcoal compared to the UNBC ash.
Chemically, the UNBC ash had lower concentrations of total C, organic C, total S
and N than the CPLP ash (Table 3). But, the UNBC ash exhibited a slightly higher
pH, K, B and Mg than CPLP ash. Both ashes exhibited similar CaCO3 equivalent
(Table 3 for brief overview; full description in Appendix C).

34

Table 3: Chemical properties of the UNBC and CPLP ash types used in the seedling pot trial. For full
characterization, refer to Appendix C.

Analyte

UNBC Ash

CPLP ash #1

pH (in water, 1:2)

11.9 (0.127)

11.1 (0.063)

CaCO3 Equivalent (%)

46.3 (1.33)

28.3 (0.345)

EC (mS/cm, 1:5)

10.1 (0.445)

5.56 (0.140)

0.13 (na)

32.5 (na)

Inorganic C (%)

1.89 (0.950)

3.28 (0.338)

Total C (%)

6.65 (0.480)

58.8 (2.62)

Total N (%)

0.037 (0.001)

0.165 (0.003)

Total S (%)

0.190 (0.008)

0.371 (0.006)

B (mg/kg)

212.3 (13.6)

145.0 (18.3)

Ca (%)

18.65 (1.111)

9.758 (0.062)

K (%)

5.1 (0.26)

2.7 (0.03)

Mg (%)

2.7 (0.13)

1.1 (0.01)

P (%)

0.8 (0.05)

0.5 (0.01)

Moisture content (%)

Macronutrients

In Table 4, trace elemental concentrations of the two bioenergy ashes used in
this study were compared to the concentration limits given in the B.C. Code of
Practice for Soil Amendments (CoPSA; Government of B.C., 2007). Both ash types
used in this study had trace element concentrations that fell below the maximum
criteria under the CoPSA (Table 4), despite the UNBC ash containing some fly ash.

35

Table 4: Concentrations (means with standard deviations, n=4) of trace elements in UNBC gasifier
and CPLP boiler ashes relative to limits within BC Code of Practice for Soil Amendments (2007).
CPLP ash #1 was used in the seedling pot trial (this chapter) and CPLP ash #2 was used in the field
trial (next chapter).
As

Cd

Cr

Co

Cu

Pb

Hg

Mo

Ni

Se

Zn

75

20

1060

150

2200

500

5.0

20

180

14

1850

<1.
0

2.6 +
0.05

30.6
+
1.01

23.2
+
3.26

81.5
+
3.73

<
0.4

2.4 +
1.9

6.4 +
0.40

55.8
+
1.48

<10

470.6 +
18.67

CPLP ash
#1 (mg/kg)

<1.
0

5.1 +
0.04

13.2
+
0.589

19.7
+
1.49

46.4
+
4.73

<
0.4

1.5 +
0.13

2.1 +
0.50

18.3
+
0.703

<10

641.2
+ 16.24

CPLP ash
#2 (mg/kg)

<4.
0

14.1
+
1.63

10.6
+
1.53

3.8 +
0.90

52.2
+
3.56

2.6
+
0.41

<2.0

4.6 +
0.68

13.1
+
1.42

<2

1206.1
+ 62.90

B.C.
Allowable
Limits*
-1
(µg g dw)
UNBC
Nexterra
(mg/kg)

To determine the amounts required for each ash type, the gravimetric
moisture content (MC) of the ash and the surface area of the planting pot were taken
into consideration. The ash amounts were corrected based on the gravimetric MC
(ω) to achieve the same application rate (dry basis) for both ashes. To do so, the
moisture content of the ashes was measured by oven-drying 5 ash samples of each
type at 105°C for 48 hours. Using the mean of the 5 samples, the following formula
was applied to determine the gravimetric MC:
ω = Mw/Md,

(Equation 1)

(where Mw is the total amount of water lost from the samples during oven-drying and Md is
the mass of the oven-dried sample)

A unitless ratio, the gravimetric MC was calculated and integrated into the
formula given in Appendix D. This calculation was used to determine the amount of
ash needed on an as-is basis, by taking into consideration the different moisture
contents of the UNBC ash and the CPLP ash. A second CPLP ash (#2) was

36

introduced (critical trace metals given in Table 4; more detail given later), due to the
amount of ash needed for the field trial. Therefore the moisture content for the CPLP
ash was based on the second CPLP ash type (Appendix D). This CPLP ash (#2)
contained approximately 76% moisture, compared to the UNBC ash, which had
0.13% (Table 3).
Another basis in choosing the application rates was the capacity of the
teabag. Due to the moisture content of the CPLP ash, it was a heavier material, but
contained less mineral content than the UNBC ash. Taking all these factors into
account, the maximum capacity for the CPLP ash in the teabag was approximately
6-7g. Given the area of a single pot was equal to 1.767 x 10-6 ha, the low rate
application corresponded to 2 tonnes ha-1 and for the high rate, 4 tonnes ha-1, if
extrapolated over a larger area. To keep consistency between the two trials, and in
an effort to isolate the seedling, the amount of ash remained the same for the field
trial (refer to Appendix D for more detail).
Teabag and broadcast application methods
Made from compostable paper derived from a blend of thermoplastic, abaca
(a plant fiber) and other cellulosic fibers (Special Tea Company, 2014), the pouches
used for the teabag (Tb) application method were purchased from Amazon
(www.amazon.ca). Measuring 62.5mm x 57mm (2.5”x 2.25”) in size, a given amount
of the ash was filled into the teabag and to seal the bag, a heated flat iron, one
typically used for hair straightening, was pressed onto the opening of the teabag. To
seal the pouch, the seam was heated for 2-3 seconds, or until the teabag was
properly sealed (Figure 3).

37

Figure 3: The flat iron, heated to medium-high heat, was pressed along the seam for 2-3 seconds to
seal the teabag closed.

For the broadcast (Bc) method, each application was spread evenly over the
surface area of the pot. For the samples treated with nitrogen, each dosage was
carefully added on the soil surface near the basal area of each seedling. For the
nitrogen application, ammonium nitrate was dissolved in water and applied at a onetime rate of 200kg N ha-1. Based on the surface area of the pot (1.767 x 10-6 ha), this
totaled 0.35g N per pot. Given the total N in ammonium nitrate is 35%,
approximately 1g of NH4NO3 (weighed out accurately as per requirements) was
dissolved in 100mL of deionized water and poured over the surface area of the pot
for each nitrogen-treated seedling.
Seedling potting and treatment placement
The lodgepole pine (Pl) and hybrid spruce (Sx) seedlings used in the seedling
pot trial were sourced from the Pacific Regeneration Technologies (PRT) nursery
located in Telkwa B.C. (PRT Summit). Both species were sown in 2012, grown for
one year in the nursery in a substrate high in peat moss. Separated by cells in a tray
of dense polystyrene, or Styrofoam, within each cell the roots grew and bound
38

around the substrate creating a root “plug”. These particular containers, known as
plug-styroblock (PSB) containers, yielded seedling stock with root plugs 4cm in
diameter and 12cm in height; hence the shorthand 412A PSB (PRT, 2014). The
seedlings were extracted, or lifted, from the styroblocks in November 2013 and
stored in a freezer for the winter.
On March 11th, 2014, the frozen seedlings were received at the EFL and
stored in the walk-in cooler (4°C) to allow them to thaw slowly for a few weeks.
During the potting phase, from March 26th to 27th, 2014, bundles of ten seedlings
were gradually taken out of the cold storage (Figure 4). In total, 95 pine and 95
spruce seedlings were randomly selected for potting. The pots were 155mm X
175mm in size (similar to #1 Black Poly Can manufactured by Anderson Die and
Manufacturing, Portland, Oregon) and received a layer 5-7 cm in thickness of
pebble-sized, expanded clay aggregates (produced by Grotek). These lightweight
and pH-neutral clay balls, which were placed at the base of each pot, helped to
conserve the amount of soil needed per pot and improve soil drainage.
When placed in the pot, each seedling was positioned slightly off-center and
approximately 1300 grams (dry weight basis) of soil were gradually added to the pot,
packed lightly around the root plug until it was submerged entirely by soil. The
seedlings were all planted as straight and upright as possible (Figure 4).

39

Figure 4: Examples of the spruce seedling stock (412A PSB) selected for the trial and how each
sample was potted.

After being potted, the 190 seedlings occupied a section in one of the
compartments of the EFL greenhouse. Placed in a random block design with species
intermixed, the pots were shuffled around the holding shelf and repositioned every
two weeks to avoid confounding effects from light and temperature (Gotelli and
Ellison, 2013). For approximately 6 weeks, from March 26th and 27th, 2014 to May
14th, 2014, the seedling pots were kept in cool conditions, usually above 11.5°C or
outdoor ambient temperatures. Maintaining cool temperatures were intended to (1)
discourage growth without the ash treatments in place and (2) to wait out winter
conditions for more suitable outplanting temperatures.
On May 14th, 2014, when the outside risk of frost had subsided, the seedlings
were moved from inside greenhouse to the EFL outdoor compound. The seedlings
were first placed in a shady section, near the EFL building, to minimize the shock of
direct sunlight. During partly cloudy weather conditions, the pots were situated in a
more permanent area in the compound yard. Though sheltered from wind, the high

40

exposure to sunlight throughout the growing season demanded regular watering of
the pots by EFL staff, in addition to rain events (Table 5).
Table 5: The monthly precipitation, maximum, minimum and mean temperatures for the summer of
2014, collected from the Prince George Airport (YXS) weather station (Government of Canada, 2014)
Month
May
June
July
August
September
October

Amount of rain
precipitation (mm)
28.7
28.5
29.2
24.5
52.8
63.2

Max. temp

Min. temp.

Mean temp.

17.3
20.5
25.1
23.9
18.8
12.4

3.0
5.6
9.5
7.9
3.4
2.7

10.3
13.1
17.3
15.9
11.1
7.6

The ash treatments were implemented on May 21st and May 22nd, 2014, and
the nitrogen treatment was administered May 28th, 2014. For the teabag (Tb)
samples, to insert the ash teabag into the pot, a small amount of soil was first
excavated using a small “auger” (Figure 5). This was done carefully to minimize
disturbance to the seedling plug on the side with the widest surface area. Seedlings
receiving the low rate of application had one teabag filled with ash buried beside the
seedling, and for the high rate, two ash-filled teabags were placed in two separate
holes. To ensure a consistent amount of disturbance for all the Tb seedlings, two
holes were excavated in each pot, equidistant from the seedling. That is, in the case
of the low rate ash treatments, one teabag of ash was buried, and a second teabag
filled with an equivalent volume of soil was placed in a second hole. Both teabags
were buried at least 0.5-1cm below the soil surface of the pot. Figure 5 shows the
approximate location of the first teabag, relative to the position of the seedling stem.

41

Figure 5: Images showing the insertion of the teabags into the seedling pots. Approximately 3-3.5 cm
from the stem, the auger was inserted and twisted gently into the soil.

The broadcast (Bc) method of application involved an even spread of the ash
over the surface area of the pot. When the pots were watered (using tapwater), it
was necessary to ensure the water penetrated the pot, so as not to overflow and
cause the runoff of the broadcast ash. Throughout the growth period, to minimize
any growth influenced by non-representative lighting, watering or temperature
conditions, the pine and spruce pots were intermixed and each row of pots was
rotated and randomly sequenced every 4 to 8 weeks, prior to snow coverage.
On November 10th, 2014, with winter approaching, the pots were placed
closer together and sawdust was packed around the outside of all the pots to
insulate them (Figure 6a). The seedlings overwintered outside until May 2015, where
the snow cover had melted off by mid-March (Figure 6b).

42

a)

b)

Figure 6: (a). The seedlings, on-site at the EFL compound, as they appeared after a snowfall on
th
December 9 , 2014. (b) By the middle of March, all of the snow had melted off and the seedlings
th
were again exposed to the weather conditions (picture taken March 15 , 2015).

Seedling vigour assessment
On May 13th, 2015, prior to measuring the heights and diameters of the
seedling samples, the vigour for each seedling was visually assessed using a scale
where one represented dead and no vigour, while the highest value of four
represented a lively, green seedling. There were slight physiological differences
between the tree species to take into account. For the pine samples, one dead
seedling, with predominantly brown or red needles, was assigned a 1 for vigour
(Figure 7a). Conversely, the highest vigour of 4 signified a live pine with deep green
needles throughout the whole stem (Figure 7d). For the spruce, where no samples
died, vigour 2 was the lowest value assigned and it represented spruce that had a
dead or irregularly-shaped leader, and faded green needles (Figure 8a). The most
vigourous spruce had new needles flushing from the bud, and the older needles
were deep green in colour (Figure 8c).

43

a)

c)

b)

d)

Figure 7: Representative pine samples are shown to give the scale used to assess vigour in the pine
samples. Image a) shows a vigour of 1, red needles dominating the stem, b) vigour 2, reduced growth
and faded green needles, c) vigour 3, good growth but faded green needles and d) vigour 4 is deep
green in colour, with newly or close to bursting buds.

44

a)

b)

c)

Figure 8: The representative spruce samples for vigour assessment shows a Vigour 2 (a) with a
stunted leader and the sample with Vigour 4 (c), deep green in colour with new needles emerging.

Stem and needle harvest
To determine the yield of aboveground biomass, the pine and spruce stems
were harvested on May 13th, 2015 (59 weeks following planting, 51 weeks following
the ash and nitrogen treatments). Using very sharp needle-nose shears, the stems
were cut just above the swelling of the root collar. Most of the live needles, plus the
whole stem trimmed to size, were placed into labeled, brown paper bags. Needles
from the current year growth were targeted and harvested from the stem and set
aside for foliar chemical analysis. The stem and needle bags were oven-dried at
70°C for 48 hours and dry weights were recorded as the samples were removed
from the oven. Pots containing soil and root biomass were stored at 4ºC until roots
could be separated from associated soil in the pots (described below).

45

Collecting the foliage for the chemical analysis involved selecting four random
samples of a possible 5 replicates from each of the 19 treatments. The needles
chosen for collection were from the leader and the upper lateral branches. For the
pine samples, 1-2 g (dry weight) of needles, and for the spruce, 0.8- 1g were
retrieved from the new growth of each stem. After oven-drying at 70°C for 24 hours,
the foliar material was pulverized to a very fine grain using a mortar and pestle, and
placed into small, labeled glass vials.
In September 2015, the foliar samples were sent for chemical analysis to the
Ministry of Environment (Environmental Sustainability and Strategic Policy Division),
located in Victoria, British Columbia. A complete listing of the foliar nutrient data is
presented in Appendix E.
Root harvest and soil sample collection
Seedling root biomass was separated from associated soil samples (for pH
analysis) during late June to early July 2015. To release the soil from the pot, the pot
was inverted and, by hand, the roots were carefully separated from the soil left to
soak momentarily in a tray filled with water. By hand, the roots were carefully
agitated and as the water in the tray became too dark with soil, it would be replaced
by fresher water. Once the water in the tray remained relatively clear, the stem and
roots were then placed on paper towel to absorb as much water as possible and
then placed in labeled, brown paper bags. After the root samples were oven-dried at
70°C for 48 hours, the biomass was weighed to determine the total yield of
belowground material.

46

To collect the soil pH samples, the pot was visualized as 3 sections, and
because the stem was off-center and the teabags were situated approximately 33.5cm from the stem (Figure 9), the soil extraction points were away from the
teabags to avoid tearing them open and contaminating the soil. For the broadcast
samples, the extraction points were the same and a relatively even amount from
each section was loosely combined into one pile and 200g was removed, placed in
labeled, plastic bags and temporarily stored in the walk-in cooler (4°C), until just prior
to the pH analysis. For samples treated with the teabag application method, while
the teabag usually remained intact within the soil column, it was important to prevent
the contamination of the soil sample with the ash from the teabag. To do so, the
teabags were carefully removed and set aside so the remaining soil could be
excavated for the sample.

Figure 9: The pH soil samples were extracted from 3 points (marked by X) and consolidated into one
sample for each seedling pot.

Four of the pots treated with teabags (Sx/UNBC/Tb/H/noN, Sx/UNBC/Tb/H/N,
Pl/UNBC/Tb/H/noN, Pl/UNBC/Tb/H/N, see Table 1 or Appendix A for the shorthand

47

treatment codes) were chosen for a more in-depth pH analysis; these samples were
included in the complete pH analysis as well. For each of the four UNBC/Tb/H pots,
pH readings for the soil column were done by dividing it into 6 sections instead of 4:
2 levels (Upper and Lower) divided into three sections (A, B, C) (i.e.: Upper ABC,
Lower ABC). The further pH analysis for these samples was intended to explore the
movement of ash solution from the teabag to the surrounding soil, for anecdotal
purposes. However, there were no apparent trends observed and therefore were not
examined in this thesis. Also the seedling samples were not excluded from the
complete pH analysis however.
For the pH analysis performed in the lab at UNBC, 10g of soil was placed into
a small cup with deionized water at a 1:2 soil-to-solution ratio. Similar to the
procedure outlined in Kalra and Maynard (1991), for the first 30 minutes, each
mixture was stirred a few times and, for another 30-minute period, the mixtures were
left undisturbed to allow for settling. After this period, the electrode of the Thermo
Orion pH meter (Model 550A) was submerged and a reading was recorded when the
meter stabilized on a certain value.
Data analysis
Using a factorial design, the 5 factors were treated as fixed effects in the
analysis of variance (ANOVA). The factors were ash type (UNBC, CPLP or no ash),
method of ash application (Bc and Tb or no- Tb), application rate (low and high), and
nitrogen (with and without). Pine and spruce seedling data were pooled and tree
species was treated as the fifth factor. For a complete list of the treatments, refer to
Appendix A.

48

The response variables analyzed in the complete factorial ANOVAs included
both the aboveground and belowground units of the seedling. Foliar nutrient levels,
soil pH and vigour assessment were other variables in the analysis. The
aboveground variables consisted of the final mean height, mean total stem growth
(Equation 2) and mean shoot mass. The belowground variables were comprised of
the final mean root collar diameter (RCD), mean total root collar growth and the
mean root mass. To examine the relationship between the above and belowground
variables, the mean root to shoot ratio (R:S) and the height to diameter ratio (HDR)
were also analyzed, as well as the total biomass.
Total growth = end of season height – initial height = Δ height
(Equation 2)
Using RStudio Inc. software (R Core Team, 2014), the distribution of the data
was tested with the Shapiro-Wilk test. Not all data were normally distributed,
however, the boxplots used to plot the data give an impression of the distribution of
the data because they represent the median, range, outliers, as well as first and third
quartiles.
The data analysis began by first examining the Control treatments (i.e.: no
ash, N- only and Tb-only) to determine if any effects associated with nitrogen and
placement alone, exclusive of ash, impacted seedling growth. Once the extent of
these 2 factors was determined, the ash type, nitrogen and species were examined
in a separate ANOVA to isolate any growth associated with the ash x nitrogen
treatments. The remaining secondary factors (i.e. application rate and placement)
were integrated into the factorial design for the complete 5-factor ANOVA.

49

While the statistical data output from R-Studio will point out whether a factor
or interaction of factors is significant, it does not show at which level this occurs (e.g.
high vs low, Pl vs Sx). To better interpret the output, any response variables deemed
significant by the ANOVA output were plotted using boxplots to better interpret at
which level the significance was likely to have occurred.

Results
Aboveground growth and mass
First, the placement and nitrogen factors were tested by analyzing the no-ash
(Tb-only, N-only) controls and the no-treatment controls (i.e. no ash, no N). In both
cases, species was an important factor for stem growth and shoot mass, but not for
the final mean height (Tables 6 & 7). However, placement was not an important
factor (Table 6). Contrarily, nitrogen addition increased the mean shoot mass of the
N-only control seedlings (Table 7), which was evident for both species, but
especially in the N-treated pine (Figure 10).
Table 6: Factorial ANOVA output for the Control samples (n= 10) compared to the Tb-only samples (n
= 10). Bolded values are significant.
Factor
species
placement
species x place

Final height
F Value p value
0.021
0.885
0.0001
0.990
0.357
0.559

Stem growth
F Value p value
22.86
< 0.001
0.880
0.362
1.902
0.187

Shoot Mass
F Value p value
6.002
0.026
0.006
0.941
0.302
0.590

Table 7: Factorial ANOVA output for the Control samples (n= 10) compared to the N-only samples (n
= 10). Bolded values are significant.
Factor
species
nitrogen
species x N

Final height
F Value p value
0.201
0.660
0.618
0.443
0.009
0.925

Stem growth
F Value p Value
44.93
< 0.001
2.006
0.176
4.095
0.060

Shoot Mass
F Value p Value
20.97
< 0.001
33.50
< 0.001
3.837
0.068

50

Figure 10: The median shoot mass for the Nitrogen-only and Control (No-Nitrogen, no treatment)
samples compared by species and N addition (P, n = 10; S, n = 10).

To determine if ash combined with nitrogen impacted aboveground growth,
the species, ash, and N factors were tested using a third-order factorial ANOVA
(Table 8). Nitrogen without ash was significant for all the response variables and
only the final mean height was significantly increased by ash x nitrogen interaction (p
= 0.03, F value = 3.50). Specifically, the UNBC ash with N combination had a strong
impact on the mean height of the pine, and less so for the spruce seedlings (Figure
11).
Table 8: The statistical summary for the ash X nitrogen factorial ANOVA (p < 0.05). The abbreviation
“ns” represents values that were not significant. Bolded values are considered significant.
Factor
species
ash type
nitrogen
species x ash
species x N
ash x N
species x ash x N

Final height
F Value p value
ns
ns
ns
ns
3.76
0.05
ns
ns
ns
ns
3.50
0.03
ns
ns

Stem growth
F Value p value
187.1
<0.001
ns
ns
4.8
0.03
ns
ns
ns
ns
ns
ns
ns
ns

Shoot mass
F Value p value
77.7
< 0.001
3.2
0.04
309.4
< 0.001
ns
ns
30.6
< 0.001
ns
ns
ns
ns

51

Figure 11: The final median height of the pine and spruce seedlings treated with ash x nitrogen
compared to the Control samples.

Incorporating the remaining factors (application rate and placement method)
into the ANOVA was limited to second-order interactions. Aside from species and
nitrogen, ash type and placement of ash were significant factors to the shoot mass,
but only slightly (Table 9). Also the rate x nitrogen had an interaction effect in all the
variables, but again with corresponding low F-values (Table 9).
Table 9: The 5 factors and 10 interactions tested using a factorial ANOVA for the height, growth and
mass variables. The abbreviation “ns” represents values that were not significant. Bolded values are
considered significant.
Factor
species
ash type
placement
rate
nitrogen
species x ash
species x place
species x rate
species x N
ash x place
ash x rate
ash x N
place x rate
place x N
rate x N

Final height
F Value p value
ns
ns
ns
ns
ns
ns
ns
ns
3.53
0.05
ns
ns
ns
ns
ns
ns
4.21
0.04
ns
ns
ns
ns
3.50
0.03
ns
ns
ns
ns
4.60
0.03

Stem growth
F Value p value
187.1
<0.001
ns
ns
ns
ns
ns
ns
4.78
0.03
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
4.65
0.03

Shoot mass
F Value p value
78.9
< 0.001
3.20
0.04
5.24
0.006
ns
ns
304.1
< 0.001
ns
ns
ns
ns
ns
ns
28.9
< 0.001
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
9.02
0.003

52

Belowground growth and mass
In the initial analysis of the placement and nitrogen factors for the controlled
groups, none of the belowground variables (final RCD, total mean RCD growth and
root mass) were significantly impacted by teabag placement. On the other hand,
nitrogen impacted all three response variables (Table 10). The species x nitrogen
interaction was significant for the root mass (Table 10), with increased root mass
occurring in the N-treated pine controls, compared to the pine without N, and spruce
altogether (Figure 12). This increase in mass attributed to the N addition was similar
to the aboveground results (see Figure 10).
Table 10: Factorial ANOVA output for the Control samples (n= 10) compared to the N-only samples
(n = 10). Bolded values are significant
Factor
species
nitrogen
species x N

Final RCD
F Value p value
1.64
0.218
14.6
0.001
0.198
0.662

Root Collar growth
F Value p Value
1.39
0.255
18.1
0.0006
0.226
0.641

Root Mass
F Value p Value
10.5
0.005
17.1
0.0008
6.251
0.024

Figure 12: The median root mass for the Nitrogen-only and No-Nitrogen (Control, no treatment)
samples compared by species. (n = 5)

53

As expected, in the three-factor ANOVA (species, ash, N), species and
nitrogen were resoundingly significant for all the belowground variables (Table 11).
For the final median RCD, additionally ash type, and species x ash, were significant
(Table 11). An increase in median RCD was observed in the spruce treated with the
CPLP ash, plus nitrogen (Figure 13). The spruce gained RCD growth from both ash
x N combinations, while, conversely, the RCD of the pine seedlings, did not see any
improvement with the ash and/or N addition. In fact, ash may have decreased the
median RCD of the ash-only treatments, in particular, the pine treated with the
UNBC ash, no N (Figure 13).
Table 11: Summary statistics for the three-factor ANOVA (p < 0.05) performed for the belowground
variables. The abbreviation “ns” represents values that were not significant. Bolded values are
considered significant.
Factor
species
ash type
nitrogen
species x ash
species x N
ash x N
species x ash x N

Final RCD
F Value p value
142.1
< 0.001
5.20
0.006
232.3
< 0.001
4.58
0.011
ns
ns
ns
ns
ns
ns

Root collar growth
F Value p value
45.7
<0.001
ns
ns
266.3
<0.001
ns
ns
ns
ns
ns
ns
ns
ns

Root mass
F Value p value
47.1
< 0.001
ns
0.06
178.1
< 0.001
ns
ns
28.1
< 0.001
ns
ns
ns
ns

Figure 13: The final median root collar diameter (RCD) of the pine and spruce seedlings treated with
ash x nitrogen compared to the Control samples.

54

When adding the additional factors (i.e. placement and rate) into the ANOVA,
the species and nitrogen again were significant. Also the application rate x nitrogen
interaction was significant for all the belowground variables, particularly the total
RCD growth (Table 12). The RCD growth of the spruce and pine seedlings was
improved by the low application rate of ash, combined with nitrogen (Figure 14). On
the other hand, for the pine the high rate of ash without the nitrogen reduced RCD
growth, when compared to the no-nitrogen pine control (Fig. 14).
Table 12: The 5 factors and their second order interactions tested using a factorial ANOVA for the
final RCD measurement, RCD growth and root mass. The abbreviation “ns” represents values that
were not significant. Bolded values are considered significant.

Factor
species
ash type
placement
rate
nitrogen
species x ash
species x place
species x rate
species x N
ash x place
ash x rate
ash x nitrogen
place x rate
place x N
rate x N

Final RCD
F Value p value
139.2
<0.001
5.09
0.007
3.28
0.040
ns
ns
221.1
<0.001
4.49
0.013
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
5.70
0.018

Root Collar growth
F Value p value
47.6
<0.001
ns
ns
4.45
0.013
ns
ns
269.2
<0.001
ns
ns
3.45
0.034
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
10.9
0.001

Root Mass
F Value p Value
48.8
< 0.001
ns
ns
6.66
0.002
ns
ns
177.4
< 0.001
ns
ns
ns
ns
ns
ns
27.4
< 0.001
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
4.78
0.030

55

Figure 14: The median RCD growth of the pine and spruce seedlings compared by ash application
rate and nitrogen addition. (n=10)

The placement factor was also significant for the RCD growth (Table 12). An
increase in total root collar growth was observed in spruce seedlings treated with
teabag (Tb) placement (Figure 15). The pine treated with the broadcast (Bc)
application method had a slightly more elevated mean RCD growth, relative to the
other pine samples (Fig. 15). These results were supported by the root mass when
plotted, where an increase was observed in the mass of the pine seedlings treated
with the Bc application method (Figure 16).

56

Figure 15: The median RCD growth of the pine and spruce seedlings compared by placement (Bc=
Broadcast; Tb= Teabag) and nitrogen addition. (n=10)

Figure 16: The median root mass of the pine and spruce seedlings compared by placement (Bc=
Broadcast; Tb= Teabag) and nitrogen addition. (n=10)

Ratios and total biomass
Species and nitrogen were notable factors throughout the three-factor
ANOVA of the root to shoot ratio (R:S), height to diameter ratio (HDR) and the total
biomass (Table 13). Ash type significantly impacted all variables in some way, either
alone or interacting with species (Table 13). This is evidenced by the decreased
HDR values of the spruce samples treated with CPLP and N (Figure 17). In
comparison, the pine N-only samples appeared to have the most decreased HDR
(Figure 17).
57

Table 13: Summary statistics for the three-factor ANOVA (p < 0.05) performed for the combined
above and belowground variables. The abbreviation “ns” represents values that were not significant.
Bolded values are considered significant.
Factor
species
ash type
nitrogen
species x ash
species x N
ash x N
species x ash x N

R:S
F Value p value
5.73
0.018
ns
ns
23.9
< 0.001
4.73
0.009
ns
ns
ns
ns
ns
ns

HDR
F Value p value
81.3
<0.001
ns
ns
107.2
<0.001
3.45
0.034
ns
ns
4.53
0.012
ns
ns

Total mass
F Value p value
80.2
< 0.001
3.6
0.03
312.7
< 0.001
ns
ns
37.7
< 0.001
ns
ns
ns
ns

Figure 17: The final median HDR of the pine and spruce seedlings compared by ash type and
nitrogen addition. (n = 10)

In the five-factor ANOVA, as well as in the previous three-factor ANOVA, the
interaction species x N was a significant factor for the total mass (Tables 13 & 14).
This is evidenced in the lodgepole pine, which experienced a significant increase in
median total mass in the N-treated samples, particularly when compared to the nonN pine and all of the spruce samples (Figure 18). Ash placement was significant for
the R:S and total mass (Table 14). For the R:S, the Tb application method reduced
the median ratio, particularly in the pine samples (Figure 19).

58

Table 14: The 5 factors, and their second order interactions tested using a factorial ANOVA for the
Root to Shoot ratio (R:S), Height to Diameter (HDR) and the total biomass (g). The abbreviation “ns”
represents values that were not significant. Bolded values are considered significant.

Factor
species
ash type
placement
rate
nitrogen
species x ash
species x place
species x rate
species x N
ash x place
ash x rate
ash x nitrogen
place x rate
place x N
rate x N

R:S
F Value p Value
6.18
0.014
ns
ns
5.37
0.005
ns
ns
25.9
<0.001
5.10
0.007
ns
ns
ns
ns
ns
ns
ns
ns
3.98
0.048
ns
ns
ns
ns
ns
ns
ns
ns

HDR
F Value p Value
79.9
< 0.001
ns
ns
ns
ns
ns
ns
103.3
< 0.001
3.39
0.036
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
4.36
0.014
ns
ns
ns
ns
ns
ns

Total mass
F Value p Value
80.2
< 0.001
3.56
0.031
5.77
0.004
ns
ns
302.1
< 0.001
ns
ns
ns
ns
ns
ns
35.3
<0.001
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
8.63
0.004

Figure 18: The median total mass of the pine and spruce seedlings compared by placement method
and nitrogen addition. (n = 10)

59

Figure 19: The median root to shoot (R:S) ratio of the pine and spruce seedlings compared by
placement method and nitrogen addition. (n = 10)

Foliar analysis
Of all the factors, the two influencing most of the elemental levels in the
foliage (i.e. Al, B, Ca, Cu, Fe, K, Mg, Na, N, P, S, Zn) were species and nitrogen
(Table 15). To better deduce deficiencies in levels of C, K, Mg, S and P, the ratios of
C:N, N:K, N:Mg, N:S, N:P were interpreted using Brockley’s (2012) revised foliar
nutrient criteria (given in Appendix E). With the exception of Zn, N, S and N:Mg,
species type dictated the majority of nutrient percentages in the foliage, most
significantly those of Ca and Al (i.e. the highest F-value; Table 15). Boron, potassium
and magnesium levels were the most susceptible to the experimental factors. Boron
in particular was significantly impacted by the ash type (p = 0.001) and the rate of
application (p = 0.007). Increased B levels were observed in the pine and spruce
seedlings treated with the UNBC ash, where nitrogen was absent (Figure 20). The
N-treated pine and spruce samples were generally lower in B levels (Figure 20).

60

Figure 20: The median total boron (mg/kg) of the pine and spruce seedlings compared by ash type
and nitrogen addition. (n = 8)

After the species and nitrogen factors, placement was the next most important
factor, influencing levels of Al, K, Mg, P and Zn (Table 15). For Al in particular, the
placement (p < 0.001) and the species x place (p < 0.001) were significant, which is
evident in Figure 21. The total Al contained in the foliage of the non-nitrogen pine
was high, especially when compared to the Control and the Bc pine sample (Figure
21; Appendix E). The Al levels of the spruce were negligible compared to the pine
(Fig. 21).

Figure 21: The median total Al (mg/kg) of the pine and spruce seedlings compared by ash placement
(Bc= Broadcast; Tb= Teabag) and nitrogen addition. (n = 8)

61

Similar to the Al levels, the nitrogen addition inversed the levels of potassium
(K; Figure 22) and the K levels were also impacted by the ash placement (Table 15).
The foliage of non-N pine seedlings had sufficient K levels (greater than 0.4; Figure
22), according to Brockley’s foliar concentration interpretation (2012). When given as
the ratio with nitrogen (i.e. N:K), the majority of the nitrogen-treated pine and spruce
were deficient in K (Pl, > 2.5, Sx, > 2.0; Figure 23); the samples that had adequate
levels of K were the Bc and Tb spruce, with no nitrogen (Pl, < 2.5, Sx, < 2.0; Figure
23).

Figure 22: The median total K (%) of the pine and spruce seedlings compared by ash placement (Bc=
Broadcast; Tb= Teabag) and nitrogen addition. (n = 8)

Figure 23: The nitrogen and potassium ratio (N:K) of the pine and spruce seedlings compared by ash
placement (Bc= Broadcast; Tb= Teabag) and nitrogen addition. (n = 8)

According to the foliar nutrient ratios set out by Brockley, only some of the Nonly spruce seedlings were nearly deficient of Mg, but the remaining samples were
62

all within adequate levels (< 15; Figure 24). Most of the nitrogen-treated samples in
both species were severely deficient in phosphorus (< 10, Figure 25). With regards
to the nitrogen and sulphur ratio (N:S), a slight to moderate S deficiency occurred in
the spruce treated with nitrogen, according to Brockley’s interpretation of foliar
nutrients (N:S = 15- 20, Figure 26; Appendix E).

Figure 24: The median nitrogen and magnesium ratio (N:Mg) of the pine and spruce seedlings
compared by ash placement (Bc= Broadcast; Tb= Teabag) and nitrogen addition. (n = 8)

Figure 25: The median nitrogen and phosphorus ratio (N:P) of the pine and spruce seedlings
compared by ash placement (Bc= Broadcast; Tb= Teabag) and nitrogen addition. (n = 8)

Figure 26: The median nitrogen and phosphorus ratio (N:S) of the pine and spruce seedlings
compared by ash placement (Bc= Broadcast; Tb= Teabag) and nitrogen addition. (n = 8)

63

With regards to the nitrogen levels, the most seedlings with adequate levels of
N were the spruce treated with nitrogen, the greatest increase seen in the CPLP with
N samples (Figure 27).

Figure 27: The median nitrogen and sulphur ratio (N:S) of the pine and spruce seedlings compared by
ash placement (Bc= Broadcast; Tb= Teabag) and nitrogen addition. (n = 8)

Figure 28: The median total nitrogen of the pine and spruce seedlings compared by ash type and
nitrogen addition. (n = 8)

64

species (sp)
ash type
place
rate
nitrogen
sp. x ash
sp. x place
sp. x rate
sp. x N
ash x place
ash x rate
ash x N
place x rate
place x N
rate x N

F Value
ns
ns
ns
ns
52.4
ns
ns
ns
41.1
ns
ns
ns
ns
ns
ns

species
ash type
place
rate
nitrogen
sp x ash
sp x place
sp x rate
sp x N
ash x place
ash x rate
ash x N
place x rate
place x N
rate x N

N*

Al

F Value
4.94
ns
13.9
ns
117.9
3.031
ns
ns
9.19
ns
ns
2.68
ns
ns
ns

p Value
< 0.001
0.014
< 0.001
ns
< 0.001
ns
<0.001
ns
<0.001
ns
ns
ns
ns
ns
ns

p Value
ns
ns
ns
ns
< 0.001
ns
ns
ns
< 0.001
ns
ns
ns
ns
ns
ns

F Value
266.8
4.43
10.4
ns
90.8
ns
12.0
ns
75.2
ns
ns
ns
ns
ns
ns

K

B

p Value
0.028
ns
<0.001
ns
< 0.001
0.052
ns
ns
0.003
ns
ns
0.072
ns
ns
ns

F Value
75.9
11.0
ns
7.61
101.6
ns
ns
3.94
ns
4.1
ns
ns
ns
ns
ns

F Value
14.40
ns
6.59
ns
42.4
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns

p Value
< 0.001
< 0.001
ns
0.007
< 0.001
ns
ns
0.049
ns
0.05
ns
ns
ns
ns
ns

P
p Value
0.0002
ns
0.001
ns
< 0.001
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns

F Value
420.7
ns
ns
ns
30.5
ns
ns
4.33
18.8
ns
ns
ns
ns
ns
ns

Ca
F Value
14.2
ns
ns
ns
9.242
ns
ns
ns
16.8
ns
ns
ns
ns
ns
ns

N:Ca
F Value
p Value
318.6
< 0.001
ns
ns
ns
ns
ns
ns
50.9
< 0.001
ns
ns
3.07
0.05
ns
ns
4.96
0.03
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns

p Value
< 0.001
ns
ns
ns
< 0.001
ns
ns
0.039
<0.001
ns
ns
ns
ns
ns
ns

N:K

p Value
< 0.001
ns
ns
ns
0.002
ns
ns
ns
<0.001
ns
ns
ns
ns
ns
ns

F Value
4.43
ns
3.11
ns
162.7
3.35
ns
ns
7.74
ns
ns
ns
ns
ns
ns

Cu

p Value
0.037
ns
0.05
ns
< 0.001
0.038
ns
ns
0.006
ns
ns
ns
ns
ns
ns

Fe
p Value
0.060
ns
ns
ns
0.052
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns

Na

N:P
p Value
0.0005
0.02
0.049
ns
< 0.001
ns
ns
ns
< 0.001
ns
ns
ns
ns
ns
ns

p Value
0.001
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
0.041

F Value
12.8
4.03
3.08
ns
224.9
ns
ns
ns
24.0
ns
ns
ns
ns
ns
ns

F Value
10.8
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
4.27

N:Mg
F Value
p Value
ns
ns
ns
ns
ns
ns
ns
ns
103.9
< 0.001
ns
ns
3.68
0.028
ns
ns
22.77
< 0.001
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns

F Value
3.60
ns
ns
ns
3.850
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns

p Value
< 0.001
ns
ns
ns
< 0.001
ns
0.01
ns
ns
ns
ns
ns
ns
ns
ns

p Value
0.0004
ns
0.054
ns
< 0.001
ns
ns
0.008
ns
ns
0.018
ns
ns
ns
ns

N:S

Mg

F Value
32.4
ns
ns
ns
164.3
ns
4.74
ns
ns
ns
ns
ns
ns
ns
ns

F Value
13.05
ns
2.97
ns
54.2
ns
ns
7.35
ns
ns
5.75
ns
ns
ns
ns

Zn
p Value
ns
ns
0.005
ns
< 0.001
ns
0.031
0.009
ns
ns
ns
ns
ns
ns
ns

S (ICAP)*
F Value
p Value
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
12.1
< 0.001
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns

F Value
ns
ns
5.45
ns
73.7
ns
3.56
7.02
ns
ns
ns
ns
ns
ns
ns

Table 15: The 5 factors, and their second order interactions tested using a factorial ANOVA for the
mean nutrient percentage for the foliar chemical analysis. Asterisk (*) signifies data that were
normalized according to Brockley, 2012. The abbreviation “ns” represents values that were “not
significant.” (n= 4)

65

Soil pH
All factors (i.e. species, ash, placement, rate and N) were significant in the
soil pH factorial analysis (Table 16). The UNBC ash initiated higher pH values in
both pine and spruce samples, most significantly in the non-N samples (Figure 28).
Of the interactions, species x ash, species x place, and species x rate were
significant, asserting that placement, ash type and rate were significant for the flux in
pH (Table 16).
Table 16: The 5 factors, and their second order interactions tested using a factorial ANOVA for the
mean soil pH values. The abbreviation “ns” represents values that were “not significant.” Bolded
values are considered significant. (n=3)
Factor
species
ash type
placement
rate
nitrogen
species x ash
species x place
species x rate
species x N
ash x place
ash x rate
ash x nitrogen
place x rate
place x N
rate x N

pH
F Value p Value
9.15
0.003
28.8
< 0.001
40.8
< 0.001
8.55
0.004
49.5
< 0.001
6.09
0.003
7.67
0.0006
14.9
0.0002
ns
ns
ns
ns
3.97
0.05
ns
ns
ns
ns
ns
ns
ns
ns

Figure 29: The median soil pH for the pine and spruce seedlings compared by ash type and nitrogen
addition.

66

The Bc placement increased the pH for both species, especially where
nitrogen was absent (Figure 29). The pH increase was more prominent in the spruce
seedlings (Figure 29). In contrast, the Tb placement had little impact on the pH,
especially where N was added (Figure 29).

Figure 30: The median soil pH for the pine and spruce seedlings compared by ash placement (Bc=
Broadcast; Tb= Teabag) and nitrogen addition.

Vigour assessment
The tendency for the nitrogen-fertilized samples to be more vigourous than
their non-nitrogen counterparts was supported by the analysis of the visual vigour
assessment (Table 17). The N factor was the most significant, yielding a mean
vigour grade of 3.5 in the N-treated samples compared to 2.4 mean vigour for the
non-N samples (Table 17). The other significant factors included the rate and the
species x ash (p < 0.05) (Table 18).

67

Table 17: The mean vigour grade for the pine and spruce seedlings based on the attributes listed in
Table 1.
Attribute
Species
Ash type
Placement
Rate
N
Control

Feature
Pl
Sx
CPLP
UNBC
Bc
Tb
H
L
N
no N
No ash
N- only
Tb only

Mean vigour
3.0
2.9
3.0
2.9
3.0
2.9
3.1
2.9
3.5
2.4
2.9
3.5
2.6

Std dev
0.6
0.6
0.6
0.6
0.6
0.6
0.6
0.6
0.6
0.6
0.6
0.4
0.7

Table 18: The 5 factors, and their second order interactions tested using a factorial ANOVA for the
mean vigour grade (n= 5). The abbreviation “ns” represents values that were not significant. Bolded
values are considered significant.
Factor
species
ash type
placement
rate
nitrogen
species x ash
species x place
species x rate
species x N
ash x place
ash x rate
ash x nitrogen
place x rate
place x N
rate x N

Vigour grade
F Value p Value
ns
ns
ns
ns
ns
ns
4.7
0.03
166.1
< 0.001
3.7
0.03
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns

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Discussion
The objective of the seedling pot trial was to determine what factors would be
a function in treating conifer seedlings with bioenergy ash treatments. Of the five
factors tested (species, ash type, placement, rate, nitrogen), the initial findings
suggested that species and nitrogen addition were the two most influential, although
ash type, application rate and placement method also played roles. The ash x N
combination increased seedling height in lodgepole pine, while the hybrid spruce
benefited by the ash x N treatment in diameter. Notably, the important factor for the
belowground growth, the foliar analysis and soil pH was the ash placement method.
This study attempted to use different methods of application to determine whether
planted seedlings would respond to ash delivered closer to the root plug. Fertilizer
delivery via teabag is said to reduce the transplant shock that occurs soon after a
conifer seedling has been planted (Reforestation Technologies International, Gilroy,
California 2018). Therefore incorporating ash with a placement method currently in
use in B.C., such as teabags, could help to improve the viability of bioenergy ash
use in the forest industry, which is the ultimate goal to this research.
To answer the first research question (whether species respond differently to
ash application), the difference in growth between the species was resounding
throughout the trial. This disparity in response between the species was attributed to
the different resource capacities of the trees. Lodgepole pine is known to respond
well to N fertilization (Brockley, 1996), which was apparent in this trial, observed in
the plots of the shoot and root masses for the controls alone (Figs. 10 & 12). Also,
pine may have had an advantage over the shade-tolerant spruce because the
environmental conditions of the trial period likely favored the pine, a species also
69

capable of enduring harsh environments (MacKinnon et al., 1999). Yet, despite the
better height growth in the pine, the foliar analysis revealed that the N-treated spruce
had adequate levels of N (Figure 27), while the N-treated pine had slightly to
moderately deficient levels (Appendix E). This suggests that the pine expended its N
resources early on, through extension of stem height, essentially giving it an
advantage over competitive plant species. While this can be seen as a benefit in
terms of overcoming competition (Grossnickle, 2012), water stress can occur if the
root system is unable to sustain adequate water levels, which would induce
transplant stress in the young seedling (Grossnickle, 2005). This can be difficult for
the seedling to overcome during these vulnerable first years of its life span.
With respect to the shade-loving spruce, it is a species not predisposed to
quick growth in the juvenile stage (Smith et al., 1997). Relevant to the second
research question (whether ash type and nitrogen influence seedling growth), hybrid
spruce appeared to prefer the CPLP ash treated with nitrogen through its growth in
root collar (Figure 13), while the pine favoured the UNBC ash with nitrogen (Figure
11). It was hypothesized that the ash type would be influential on seedling growth,
and that the high-carbon CPLP ash would act somewhat similar to a slow-release
fertilizer compared to the finer-textured UNBC ash, which would resemble a fastrelease fertilizer. Therefore we could infer that the species would have opposite
preferences when considering ash types, bearing in mind that spruce has been
unresponsive to ash treatments in the past. For example, the 5 year-old Norway
spruce (Picea abies) stand in southwest Sweden (Wang et al., 2007) and the white
spruce (Picea glauca) seedlings in Saskatchewan, Canada (Staples and Van Rees,
2001) did not respond well to ash application. As Staples and Van Rees (2001)
70

found, spruce seedlings preferred the low rate of ash, while a high rate (5 Mg ha-1)
resulted in a decrease in spruce growth. The preference of a low rate of application
was also represented in this study by the increased root collar diameter observed in
both species treated with a low rate of 2 tonnes ha-1 (Figure 14).
The presence or absence of nitrogen was undoubtedly a significant factor
throughout the seedling pot trial and it was expected that nitrogen would have a
positive interaction with the ash (Jacobson, 2003; Saarsalmi et al., 2006). This was
represented in the final median height of the pine seedlings treated with UNBC x N,
and also the final median RCD of the hybrid spruce treated with CPLP x N. The
addition of ash in conjunction with nitrogen can increase stand volumes of older pine
and spruce stands in poor quality sites, such as the N-deficient sites in Finland
(Saarsalmi et al., 2014). Another advantage to combining the two is that ash can
prolong the effects of the nitrogen addition (Saarsalmi et al., 2014). However, it is
hard to predict how long the ash x N combinations will persist and, in this case, it
could depend on the ash type. For instance the UNBC ash could have short-lived
result, due to its fine texture. Ash that has not been aggregated into pellets or
solidified in a more contained state is prone to increased leaching of calcium over
time (Steenari et al., 1999; Pitman, 2006). As the calcium dissipates, the pH lowers,
causing P, Mg and other metals to release and leach more rapidly away (Steenari et
al., 1999).
The third research question addressed the application technique, or
placement, as well as the rate of application. The placement technique of the ash
has not been widely studied and broadcast application seems to be the typical ash
delivery system. Broadcast spreading of ash could be optimized by incorporating the
71

ash into the upper soil horizons, for example, in the agricultural setting where a
cultivator can be used to mix in the ash into the upper 10cm of the soil (Lupwayi et
al., 2009). However, this is not always practical in a forestry setting. By employing
the teabag method, which is a fertilization practice that has assisted in reforestation
success (RTI, 2018), we could attempt to determine whether placing the ash closer
to the root plug would improve the seedling chances at survival. Belowground
variables were particularly susceptible to the placement factor, with root mass and
final mean RCD impacted. A small increase in the RCD of the spruce treated with
the Tb placement was contrasted by the minor increase observed in the pine treated
with the Bc spread. As such, when considering the method of ash dispersal, not only
should the site and accessibility be considered, but also whether it is compatible with
the species selected for reforestation.
Although all the factors had some impact on soil pH, after nitrogen the ash
placement by broadcasting (Bc) or by teabag (Tb) method, was the next most
dominant factor. Soil pH increases were observed in both species where seedlings
received the Bc method, with no nitrogen added (Figure 29). The difference in ash
concentration between a broadcast spread over the surface of the pot, compared to
pots containing a compact and submerged ash teabag, would likely contribute to the
soil pH increase. The teabags, though weathered at the end of the study period, may
have needed further decomposition (i.e. dissolution) over time to allow the ash to
infiltrate the soil enough to influence the soil pH. Considering this, the teabag
method could be a favourable dispersal method if a delay in nutrient release is
advantageous. However, compared to the process of granulating or self-hardening
ash, inserting ash into teabags may not be appealing. However, ash teabags could
72

help to minimize dust issues associated with ash dispersal, one of the many
challenges associated with ash application.
Similar to Domes et al. (2018), increased soil pH was observed where a lowcarbon ash (similar to the UNBC ash type in this trial), was applied to young, 18 and
25-year old spruce stands. Our results suggested the N addition stabilized the pH
somewhat. This was likely attributed to the oxidation of the N- fertilizer by soil
microbes, that is, the conversion of ammonium to nitrate (i.e. nitrification), which can
generate strong acids, inducing a lower, more acidic soil pH (Brady & Weil, 2007).
The neutralizing capacity of the ash coupled with an ammonium-based fertilizer
could be ideal for reforestation, especially on N-deficient sites, like those renowned
throughout the Central Interior B.C.
Ash placement also influenced some important elements in the foliage, such
as Al, B, K, Mg and P (Table 15). This has implications for the Al that can be
mobilized in an acidic soil environment, which can be problematic for waterways
(McHale et al., 2007) and introducing this element through ash in areas prone to
acidity, may not be the best practice. However, for all the ash types used in these
trials, the Al levels were quite low in the CPLP ashes and, with regard to the UNBC
ash, resembled the Al levels of the potting soil (and field trial soil). The nitrogen
factor was undoubtedly a player in minimizing the Al uptake in the foliage, or
perhaps it could be attributed to the pH change, because the non-N pine samples
were all quite high in Al (Figure 21).
Another interesting trend observed in the foliar analysis was the B and K
levels, which appeared to be influenced by the nitrogen addition. Both elements had
increased levels in the non-nitrogen treated samples, but only the pine seedlings that
73

did not receive nitrogen had adequate levels of K, according to the ranges set out by
Brockley (2012). Where ash is deficient in K, a supplemental application (e.g.
potassium chloride, K fertilizer or biotite) can help to enhance the ash as a fertilizer.
Moilanen et al. (2012) found that adding a K supplement to peat ash, an ash with low
K content, was an improvement to stand volume. The increase in growth was greater
when the peat ash was combined with KCl, a result slightly higher than the biotite
supplement, but both more effective than ash alone (Moilanen et al., 2012).
All samples had adequate levels of B (Figure 20), and in fact, the N addition
appeared to have reduced the B intake for both species, particularly those treated
with UNBC ash. While stands in the Central Interior of B.C. are known to have B
deficiencies, perhaps omitting the N application will enhance the input of B in an ash
fertilization application, depending on the aim of the treatment. However, these
levels of adequacy may be short-lived, because unlike Ca and P, which persist in
ash fertilizers, boron is one of the elements easily released from ash, along with K,
sodium (Na) and sulphur (S) (Nieminen et al., 2005). Other notable elements in the
foliage included the Ca levels in the lodgepole pine, which differed from those of the
spruce. While neither species was deficient, the levels of Ca in the spruce were
consistently twice as high as those from the pine, based on the levels set out by
Brockley (2012).
The levels of nutrients in the foliage of two very opposite species would have
been interesting to contrast with a third species type, for example, Douglas-fir
(Pseudotsuga menziesii). The challenges with establishing Douglas-fir in field
situations, could be aided by the input of ash. Perhaps tree and plant species, like

74

the Douglas-fir and the lodgepole pine, originating from wildfire-prone regions are
better adapted to capitalizing from the input of ash.
There were some limitations associated with the seedling pot study. Firstly,
the time period relative to the entire life of a conifer was quite short. However, with
the more intensive analysis of the seedling structure, it was worth it to determine, if
any, the translocation of ash nutrients within the initial stages of seedling
establishment. Further studies could examine the translocation of the ash nutrients
within the seedling and soil over a longer period of time.
Essentially the initial years of establishment are the most crucial for a
seedling, and maximizing survival for planted seedlings is a goal for forest managers
and silviculturalists. There are increasingly more and more factors to consider, such
as the spacing or density of the seedlings, the seedling stock (e.g. species or size)
selected for planting, and also if a fertilizer would benefit the seedling in the longterm.

75

Chapter 3 Field trial: Conifer seedlings fertilized with bioenergy ash
and nitrogen in SBSwk1 harvest cutblock
Introduction
With the production of bioenergy increasing in Canada (Bradburn, 2014), the
management and disposal of the subsequent ash by-products need to be taken
seriously. In 2009, the Government of Canada created the Pulp and Paper Green
Transformation Program, which incentivized pulp and paper mills to integrate
cogeneration bioenergy power plants into their infrastructure (Bradburn, 2014). With
the encouragement for more of this energy source, there also needs to be
concessions made for the expense of disposal or utilization of ash. The economics
of utilizing ash on forestlands will depend largely on the pre-disposal treatment (i.e.:
ash stabilization), transportation costs and costs for ash dispersal (Hope et al.,
2017). In addition to the arduous and logistically difficult nature of actual ash
(Hannam et al., 2016), if ash-spreading machinery is being used, there will also be
higher transport costs and extra planning will be needed (Hope et al., 2017). As it
stands, landfilling ash is more cost-effective, although ash application in forests,
presumably clear-cuts, can be competitive provided that the distance from source to
site is within 100km (Hope et al., 2017). Also if costs can be reduced in the pretreatment, in transportation or in the ash dispersal phase, the appeal of ash
application will only be enhanced (Hope et al., 2017). Improving our practices and
developing innovative methods to help save costs would be one of the objectives for
studying the use of ash on a large scale in the forests of Central Interior BC.
If the popularity of bioenergy continues to rise, not only does the surplus of
ash become an issue, but it could also have implications for harvesting intensities.

76

As some Scandinavian countries have found, removing the majority of the biomass
associated with the forest stand can be detrimental to the long-term productivity of
the site (Olsson et al., 1996; Saarsalmi et al., 2010). Satisfying a demand for
bioenergy by increasing the removal of important coarse woody debris (CWD), which
plays fundamental roles in the nutrient cycling of a forest ecosystem (Harmon et al.,
1986; Stevens, 1997), should be avoided. Presently, many woody materials already
go unused in the forest industry, beginning at the road-building and harvesting
phases. According to the Forest Practices Board of BC, between 2004-2008, 15
million cubic meters of harvested wood became waste, which equated to 4.3% of the
total volume harvested annually during that time period (Forest Practices Board,
2010). These wood wastes range from debris scattered throughout the cutblock, or
along road right-of-ways, or wood that cannot be removed due to safety concerns
(FPB, 2010). Some of this debris contributes to the CWD content, however, the
wood wastes that are piled and burned on-site are the wasted resource. The
utilization of woody residuals from harvest blocks for energy, as well as the milling
wastes that currently make up the feedstock for bioenergy, and returning the pure
ash back to the site of origin, would be a holistic and advanced approach to forestry
in B.C.
The ultimate goal in ash utilization is to use the most ash that is operationally
and economically feasible, and with the least detriment and most benefit to the
ecosystem. By recreating the seedling pot trial in the field, we were able to revisit our
study objectives, but in a natural setting and on a larger scale. Located in the Aleza
Lake Research Forest, a cutblock harvested in Winter 2013 was the site for the field
trial. In Spring 2014, two native conifer species were planted and subjected to the
77

same 19 treatments as the seedling pot trial (Appendix A) to determine whether ash
enhances seedling growth. Hybrid white spruce (P. glauca x engelmannii) and
lodgepole pine (Pinus contorta, var. latifolia) were treated (via ash and/or N addition
to soil) shortly after being planted out and measured before and after two growing
seasons. Analyses performed on the growth increment, as well as height and
diameter measurements, were intended to help determine whether the factors (tree
species, ash type, ash placement, application rate, nitrogen) influenced the growth
response, if any occurred. It was hypothesized that ash and nitrogen combined
would increase seedling growth and responses would differ with species. Secondary
factors such as ash placement method and application rate were also expected to
impact the response of the seedlings to the ash treatments.

Materials and Methods
Site description
Located within the traditional territory of the Lheidli T’enneh First Nation, the
Aleza Lake Research Forest (ALRF; 54°07′ N, 122°04′ W) is an approximately 9000hectare tenure situated at the foothills of the Cariboo Range in the northern
Canadian Rocky Mountains. The Biogeoclimatic Ecological Classification (BEC)
zone that dominates the ALRF is the Sub-Boreal Spruce (SBS), wet- cool subzone
(wk), called the Willow variant (1). The SBSwk1 zone is known to be the wettest,
snowiest and coolest of the SBS zones in the Cariboo Range (DeLong et al., 2003).
Between 600-750 m above sea level, the ALRF consists of rolling terrain, with
gullies throughout, and wetlands along the floodplains of the Bowron River: the area
has a mean annual temperature of 3.1°C and a mean annual precipitation of

78

894.9mm (Jull & Karjala, 2005). The dominating coniferous species in the Willow
variant include hybrid white spruce (Picea glauca x engelmannii), subalpine fir (Abies
lasiocarpa), lodgepole pine (Pinus contorta var. latifolia), with scattered Douglas-fir
(Pseudotsuga menziesii) in the drier sites (DeLong et al., 2003; Jull & Karjala, 2005).
Deciduous species include paper birch (Betula papyrifera), trembling aspen (Populus
tremuloides) and black cottonwood (Populus balsamifera ssp. trichocarpa); species
such as Devil’s Club (Oplopanax horridus), black twinberry (Lonicera involucrata),
thimbleberry (Rubus parviflorus), black currant (Ribes lacustre) and oak fern
(Gymnocarpium dryopteris) make up some of the ground vegetation that dominated
the study site.
The soils at ALRF are generally fine-textured, of glaciolacustrine origin and
mainly Luvisols with a prominent Bt horizon resulting from clay particles migrating
down from the upper soil horizons (Jull & Karjala, 2005). Upper soil layers are made
up of a thin organic layer overtop a granular soil horizon, promoting ideal drainage if
on sloping terrain (Jull & Karjala, 2005). According to the edatopic grid from the Land
Management Handbook (LMH) for the Southeast portion of the Prince George
Forest Region, the site series (SS) that encompassed the trial site was SS8
(Appendix H: Edatopic Grid). Soils occurring in SS8 are “rich to very rich” soils and
“subhygric” soil moisture regime (Steen & Coupé, 1997; DeLong et al., 2003).
The site for the field trial was located in Block 26 (Appendix B), which was a
cutblock harvested in 2013 using the clearcut system, with reserves. On May 22nd
2014, a section of the block approximately 3.1ha in size was partitioned off for this
project (see Figure 31a; full map in Appendix B). The study site had relatively flat
ground, homogenous plant species and the soils were primarily silt loams (Appendix
79

G). The boundary was marked with orange flagging ribbon and wooden stakes were
posted at each of the four corners as markers. The site was then divided into 6 subsections, with approximately the same area, three sections for each tree species
(see Figure 31b; full map in Appendix B).

Figure 31: a) The field trial area bordered a Riparian Reserve, referred to as a Wildlife Tree Reserve
(WTR) in the legend of the complete map in Appendix B. Green sections (A, C and E) were planted
with lodgepole pine (Pl), and pink sections (B, D, F) represent where hybrid spruce (Sx) were planted.
b) The approximate location of all the plots, each number corresponding to the treatments listed in
Appendix A.

Trial design
The same experimental treatments employed in the seedling pot trial were
incorporated into the field trial (see Appendix A for list of treatments). The tree
species (lodgepole pine, Pl and hybrid spruce, Sx), types of bioenergy ash (UNBC
80

and CPLP), two methods of application (Broadcast, Bc and Teabag, Tb), and the
application rates (low, 2 tonnes ha-1 and high, 4 tonnes ha-1, dry basis) remained
unchanged for the larger-scaled field trial. For simplicity, the pot size used in the
seedling pot trial (i.e. surface area for calculating application rates) was adopted for
the field trial to keep uniformity in the amounts of ash, particularly for the teabag
treatments.
The section of Block 26 allocated to the field trial was divided into 6 subsections and 19 plots were established, for a total of 114 plots over the whole 3.1ha
trial area (Figure 31b). In the northernmost parcel (Section A), lodgepole pine was
planted, with spruce planted in the adjacent section to the south (Section B). The
species planted was alternated through the remaining 4 sections, ending with spruce
in Section F (Figure 31b).
In each plot, six seedlings received a treatment that was randomly selected
from one of the 19 different combinations by pulling numbers from a hat (see
Appendix A for list of each number and the corresponding treatment); control
seedlings received no treatment and were independent of the treatments, on
account of their distance from the treated samples. A total of 684 seedlings were
tracked over the course of two growing seasons (Summer 2014 and 2015) and a
winter season (Winter 2014-2015).
Seedling planting and plot set-up
On May 23rd 2014, the hybrid spruce seedlings were planted in three of the
parcels (Sections B, D and E) allocated to the field trial on Block 26 (see map in
Appendix B). The seedlings, which were sourced by the timber sale licensee, were

81

planted by professional treeplanters from a silviculture company based in Prince
George, B.C. Starting June 5th 2014, three ALRF research associates planted the
lodgepole pine seedlings in the remaining three sub-sections (A, C and E). The pine
seedlings were sourced from the PRT Red Rock nursery, located in Red Rock B.C.,
25 km south of Prince George, B.C. and were a similar stock as the seedlings from
the pot trial (i.e. 412A PSB, see page 38 for more information). During the time when
the seedlings were outside on the cutblock (prior to planting), they were stored in
waxed nursery boxes and placed under a Silvicool tarp (Bushpro Supplies Ltd,
Vernon, B.C.). The Silvicool tarp is intended to keep the seedlings at a constant
temperature close to that of “deep shade” (Bushpro, 2018).
The lodgepole pine and hybrid spruce seedlings were planted at a density of
1800 stems per hectare, which equates to 2.5m spacing between each seedling.
The spacing between the seedlings was checked using a 3.99m plot representing
0.005ha or 50m2. The equivalent density for 1800 stems ha-1 per 3.99m plot is 9
seedlings. This plot size was also used as the metric for establishing the study plots
in each of the six planted sections.
Treeplanters wore a set of treeplanting bags, which consisted of three 14”
soft, vinyl “buckets” positioned on both sides of the hips and one in the back
(Bushpro, 2018). Each bucket contains a Silvicool sac that held the seedlings and,
similar to the tarp, helped to keep them at a cool temperature and prevent them from
drying out (Bushpro, 2018). Each bucket carries a manageable number of
cellophane-wrapped bundles of seedlings, which contained 10 seedlings each. As
the planter would progress, bundles were unwrapped, kept in contact with a moist
piece of foam and placed in the most convenient bucket for the planter to pull them
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from. While walking, the planter would choose a microsite for the seedling, and with
the shovel in-hand, the planter would open a hole at a minimum distance of 2.5m
from the previous seedling. With a planting shovel in one hand, the opposite hand
would grab the seedling and insert the root plug into the hole opened by the shovel.
Prior to closing the hole, the planter would ensure the root plug and stem were as
straight as possible. To close the hole, a gentle boot kick or closing by hand was
usually sufficient.
Once all the lodgepole pine and hybrid spruce seedlings were planted, the
plot centers were established. In each section, nineteen plots representing 19
different treatments were placed in a grid-like pattern (see Figure 31b). Using a large
measuring tape, 10 to 12m were measured between each plot center to ensure the
plots were independent of each other. A metal wire marker with bright flagging tape
was placed at the plot center as an identifier. Attached to each marker was a
numbered tag chosen at random from a bag, each number representing a treatment
(Appendix A).
In each marked plot, six planted seedlings from a possible 8 or 9 within the
3.99m plot were selected for the trial. Each seedling was tagged using an aluminum
tag stamped with an identification number, which was tied loosely to the base of the
tree stem with a metal twist tie (Figure 32).

83

Figure 32: A hybrid spruce seedling with an identification tag attached. The cutout of the seedling pot
can be seen at the base of the tree, which helped to delineate the area receiving the broadcast
spread of ash and nitrogen. The second image shows a pine seedling with some representative site
plant species that would represent some potential competition for the seedlings. Photo credit: H.
Massicotte

Treatment placement
The two ash types used for the ash treatments were sourced from local
bioenergy producers that utilize wood wastes essentially derived from nearby
forests. The ash sourced from the UNBC Nexterra gasifier located on campus in
Prince George, B.C., was collected on July 13th, 2012 and consisted of both bottom
and fly ash. The UNBC ash was compared to an ash originating from a boiler
bioenergy system (#2) located at a Canfor Pulp Limited Partnership (CPLP) pulp
mill, also in Prince George B.C. Collected on January 10th, 2013, the CPLP ash was
much chunkier and more moist than the UNBC ash, which was more fine and with
less moisture (Table 19; full description in Appendix C). The second CPLP ash
(CPLP #2) was used for this trial (Table 19). Predetermined amounts of the two ash
types (see Appendix D for sample calculations) were weighed and placed into either
teabags for the Tb method or plastic bags for the Bc technique. A solid form of

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nitrogen (ammonium nitrate; NH4NO3) fertilizer was weighed and inserted into paper
envelopes for storage until application in the field. On July 10th, 11th and 15th, 2014,
the premeasured ash and nitrogen fertilizer treatments were applied to six
designated seedlings within each one of the plots contained in the six sub-sections.
Table 19: Chemical characterization of the two ash types, UNBC and CPLP, used in the field trial. Full
description is given in Appendix C.
Analyte
pH (in water, 1:2)

UNBC Ash
11.9 (0.127)

CPLP Ash #2
10.4 (0.108)

CaCO3 Equivalent (%)

46.3 (1.33)

44.6 (1.44)

EC (mS/cm, 1:5)

10.1 (0.445)

9.09 (0.279)

Moisture content (%)

0.13 (na)

58.8 (1.63)

Inorganic C (%)

1.89 (0.950)

2.81 (0.335)

Total C (%)

6.65 (0.480)

50.5 (2.55)

Total N (%)

0.037 (0.001)

0.190 (0.001)

Total S (%)

0.190 (0.008)

0.51 (0.051)

B (mg/kg)

212.3 (13.6)

142.6 (8.431)

Ca (%)

18.65 (1.111)

14.4 (0.625)

K (%)

5.1 (0.26)

3.2 (0.03)

Mg (%)

2.7 (0.13)

1.2 (0.08)

P (%)

0.83 (0.05)

0.60 (0.04)

Macronutrients

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Placing the teabag treatment into the soil involved prying open a hole, by
hand, with a treeplanting shovel approximately 10cm, or the width of the shovel
blade away from the seedling (see Figure 33 for an example). Keeping the hole open
with the shovel, the teabag was inserted into the hole so that the bottom of the bag
was at a depth of about 10cm. Closing the hole, y hand or with a gentle boot kick,
would place the top of the teabag approximately 2-4cm below the surface, organic
layer included. The high rate of application called for two teabags to be inserted into
two different holes, to attain the rate of 4 tonnes ha-1 rate (dry basis). Using a shovel,
another hole would be cut at a 90-degree angle from the first shovel-cut, equidistant
from the seedling.

Figure 33: A planter demonstrates how the teabag treatment was inserted near a pine seedling using
a treeplanting shovel and how it appeared after the hole was closed. Photo credit: H. Massicotte

86

Figure 34: An example of how the broadcast treatment was placed. The ash and/or nitrogen was
spread evenly over the surface area of the pot template. Photo credit: H. Massicotte

For the broadcast method of ash application, the ash was applied by
spreading it over a cut-out of a pot used in the seedling pot trial to delineate the
surface area coverage (Figure 34). For the nitrogen-treated seedlings, the premeasured dose of ammonium nitrate pellets were scattered around the stem (refer
to Figure 34).
Soil collection and characterization
Prior to the ash application in the field, we collected soil samples from nine
soil pits randomly selected in order to characterize the baseline soil properties of the
site. These soil pits were located at A14, A20, B3, C3, C4, D10, E7, F6, F15 (refer to
Figure 31 for approximate locations). Three soil horizons overall were identified
(LFH, Ae, Bm, Bg for F15) and samples for each horizon were taken from all nine
pits. The 9 samples from the soil pits were organized into 3 separate categories
(A/B, C/D, and E/F). Three composite samples were created by combining equal
87

amounts from each of the collection zones, for each soil horizon. Samples were sent
away to the Ministry of Environment (Environmental Sustainability DivisionKnowledge Management Branch) for analysis in Victoria, B.C. Fairly low in pH, the
field site’s soil consisted of a thin LFH layer, with silt loam Ae and Bm/Bg horizons
(Table 20; refer to Appendix G for full characterization). A relatively acidic soil, the
CEC was greatest in the LFH layer, as was the total carbon and boron levels (Table
20). Available P and Mg increased with depth, the highest amounts found in the Bm
horizon.

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Table 20: Chemical characterization of the soil type found at the field trial site, located in the SBSwk1Willow variant. For full description, refer to Appendix G.
LFH n = 3

Ae n = 3

Bm n = 3

Sand (%)

na

39.9 (10.3)

45.3 (7.48)

Silt (%)

na

49.6 (7.75)

44.8 (7.77)

Clay (%)

na

10.6 (2.65)

9.90 (2.03)

pH (soil: water, 1:1)

4.9 (0.31)

4.7 (0.14)

5.1 (0.12)

CEC (cmol /kg)

12.5 (1.03)

4.9 (0.94)

4.9 (0.98)

Available P (mg/kg)

27.2 (11.3)

31.6 (24.6)

77.7 (64.2)

Total C (%)

19.1 (7.29)

1.57 (0.130)

2.34 (0.935)

Total N (%)

0.876 (0.330)

0.112 (0.009)

0.134 (0.047)

Total S (%)

0.089 (0.033)

0.011 (0.002)

0.017 (0.007)

B (mg/kg)

5.37 (0.672)

2.43 (0.228)

< 2 (na)

Ca (%)

0.756 (0.085)

0.446 (0.078)

0.497 (0.055)

K (%)

0.256 (0.041)

0.292 (0.014)

0.271 (0.030)

Mg (%)

0.205 (0.042)

0.334 (0.048)

0.605 (0.030)

+

Measurements and analyses
Measurements of the stem height and root collar diameter (RCD) were
recorded twice during the field trial. Initial measurements were taken at the same
time the treatments were applied, on July 10th, 11th and 15th, 2014. Final
measurements were taken after the second growing season was presumably
complete (i.e. after the buds had hardened off) on August 12th, 13th, and 14th, 2015.
The height measurement was taken from the base of the stem to the top of the
leader bud. To account for the non-circular stem, two RCD measurements were
recorded from the lowest possible point of the stem. Seedling vigour was assessed

89

at the time that final measurements were recorded; however, seedling vigour is not
presented or interpreted in this chapter due to time constraints.
Data analysis was carried out in a similar manner as that done for the seedling
pot study. However, to avoid destructive measurements, such as total belowground
mass of the seedling, measurements were limited to growth increment, final height
and final root collar diameter. Using R-Studio, the data was analyzed to determine
whether any of the factors (tree species, ash type, application rate, ash placement,
nitrogen) were significant to the response of the seedlings to treatments. In the initial
analysis, only the three control treatments (No ash/No nitrogen, N-Only, Tb-Only)
were tested using a factorial ANOVA. Once the effects of placement and nitrogen
were isolated in the controls, the ash and nitrogen interaction was tested for all the
samples, including the controls. Due to the limited output of R, if a factor (e.g.: ash
type) yielded a low p-value (p < 0.05), a boxplot was used to interpret at which level
this significant effect occurred. The final analysis included the remaining application
rate and placement factors to complete the 5-factor multi-factorial ANOVA.

Results
Analysis of control treatments
To determine whether the placement of the teabag and the nitrogen
treatments, both exclusive of ash, were significant factors to seedling growth, the
control samples (No ash/No nitrogen, N-Only, Tb-Only) were first analyzed for
variance (Tables 21 and 22). With respect to the teabag placement, aside from
species being a significant factor for most of the response variables (with the
exception of the final RCD, Table 21), species x placement interaction had a

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significant impact on the total height growth (p = 0.02, Table 21). The teabag
placement may have reduced lodgepole pine height, and conversely in the hybrid
spruce, may have increased it (Figure 35).
Table 21: Factorial ANOVA results for the Control samples compared to the Tb-only (n = 72). Bolded
values are significant.
Factor
species
placement
sp x place

Final height
F Value p value
6.40
0.014
2.38
0.127
2.95
0.090

Total growth
F Value p value
12.07
0.0009
0.424
0.517
5.27
0.025

Final RCD
F Value p value
0.147
0.702
1.62
0.208
2.95
0.091

RCD growth
F value p value
9.43
0.003
0.510
0.478
1.23
0.272

HDR
F value p value
11.5
0.001
0.904
0.345
0.483
0.489

Figure 35: The median total height growth of the pine (Pl) and spruce seedlings (Sx) treated with
teabags (Tb-Only) compared to the control (no-ash) seedlings.

Nitrogen was a significant factor for the final height variable and the height to
diameter ratio (HDR), but only slightly (Table 22). Interestingly, the nitrogen may
have reduced the growth of the N-treated seedlings, in a comparable way for both
species (Figure 36).
Table 22: Factorial ANOVA results for the Control samples compared to the N-only (n = 72). Bolded
values are significant.
Factor
species
nitrogen
sp x N

Final height
F
p
Value
value
1.08
0.302
3.82
0.055
0.035
0.851

Total growth
F
p
Value
value
28.5
<0.001
0.531
0.468
1.183
0.281

Final RCD
F
p
Value
value
1.03
0.314
0.079
0.779
0.961
0.331

RCD growth
F
p
value
value
14.51
0.0003
0.056
0.813
0.011
0.917

HDR
F
p
value
value
4.98
0.029
6.75
0.012
0.317
0.575

91

Figure 36: The final median height of the pine (Pl) and spruce (Sx) seedlings treated with nitrogen (Nonly) compared to the control (no-ash, no N) seedlings.

Factorial analysis
In the second stage of the ANOVA, where ash and nitrogen factors were
analyzed for the pine and spruce, species and nitrogen were the most significant
factors, but not for all the variables (Table 23). The total height growth, a variable not
heavily influenced by nitrogen alone, was the only variable that was impacted by ash
x nitrogen combination (Table 23). Lodgepole pine growth did not appear to be
significantly impacted by ash, fertilizer N or the ash x N combination, and, in
contrast, hybrid spruce seedling growth responded differently to N addition,
depending on the type of ash used (Figure 37). Spruce growth benefited the most
when UNBC ash was applied without fertilizer N. The nitrogen added to the CPLP
ash also seemed to favour the spruce seedling growth (as compared to non-N
treatment, Figure 37).

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Table 23: Statistical summary for the three-factor ANOVA (p < 0.05) performed for all the growth
variables (final height, total growth, final RCD, RCD growth, HDR).
Factor
species
ash type
nitrogen
species x
ash
species x
N
ash x N
species x
ash x N

Final height
F
p
Value value
37.2
<
0.001
ns
ns
ns
ns
ns
ns

Total growth
F
p
Value value
65.1
<0.001

Final RCD
F
p
Value value
ns
ns

RCD growth
F
p
Value value
28.7
<0.001

HDR
F
p
Value value
48.4
<0.001

ns
ns
ns

ns
ns
ns

ns
5.07
ns

ns
0.024
ns

ns
4.9
ns

ns
0.03
ns

ns
9.13
ns

ns
0.003
ns

ns

ns

ns

ns

ns

ns

ns

ns

ns

ns

ns
ns

ns
ns

3.14
ns

0.044
ns

ns
ns

ns
ns

ns
ns

ns
ns

ns
ns

ns
ns

Figure 37: The total median height growth (cm) of the pine and spruce seedlings treated with ash x
nitrogen compared to Control (Cont; no ash, no N) samples.

In the final stage of analysis, all the factors were integrated into the multifactorial ANOVA and it was determined that ash with N (ash x N) became significant
for the final height, as did ash type, for total growth (Table 24). Similar to the growth
plots in Figure 37, the UNBC ash alone increased hybrid spruce height the most
(Figure 38). Similarly the CPLP with N was the only ash x N combination that
initiated an increase in hybrid spruce growth over the no-nitrogen counterpart (Figure
38). However, another ash x N combination (UNBC ash x N) increased the final

93

height of the lodgepole pine seedlings, but only slightly compared to the other
treatments (Figure 38).
Table 24: The 5 factors and their second order interactions tested using a factorial ANOVA for the
final height, total growth, final RCD, total RCD growth and HDR. The abbreviation “ns” represents
values that were not significant. Bolded values are considered significant.

Factor

Final height

Total growth

species (sp)
ash type
placement
rate
nitrogen
sp x ash
sp x place
sp x rate
sp x N
ash x place
ash x rate
ash x N
place x rate
place x N
rate x N

F
Value
37.6
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
3.35
4.51
4.45
ns

F
Value
66.1
2.5
ns
ns
ns
ns
ns
ns
ns
ns
ns
3.30
6.04
5.24
ns

p value
<0.001
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
0.035
0.034
0.035
ns

p
value
<0.001
0.09
ns
ns
ns
ns
ns
ns
ns
ns
ns
0.040
0.014
0.022
ns

Final RCD
F
Value
3.49
ns
ns
ns
3.97
ns
ns
ns
ns
ns
ns
ns
4.55
ns
ns

p
value
0.062
ns
ns
ns
0.047
ns
ns
ns
ns
ns
ns
ns
0.033
ns
ns

RCD growth
F
value
28.9
ns
ns
ns
4.3
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns

p
value
<0.001
ns
ns
ns
0.04
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns

HDR
F
value
50.2
ns
ns
ns
9.45
ns
ns
ns
ns
ns
ns
ns
23.6
4.75
ns

p
value
<0.001
ns
ns
ns
0.002
ns
ns
ns
ns
ns
ns
ns
<0.001
0.029
ns

Figure 38: The median final height (cm) of the pine and spruce seedlings treated with ash x nitrogen
compared to Control (Cont: no N, with N) samples.

For the final RCD variable, nitrogen and placement x rate were significant
factors (Table 24). An increase in RCD growth occurred in the Tb-treated spruce, a
growth trend that was first noticed in the analysis of the height of the Controls
(Figure 35). The low rate of application, combined with the Tb placement, was the
94

combination that initiated the highest growth response in the spruce seedlings
(Figure 39). Conversely, the RCD of the lodgepole pine seedlings did not seem to
benefit from either type of placement method, considering the diameter of the
untreated Control had the highest increase (Figure 39).

Figure 39: The final root collar diameter (RCD) of the pine and spruce seedlings treated with
placement x rate compared to the Controls (no ash and Tb-Only).

Combining the variables into the height to diameter ratio produced the lowest
F-value for the placement x rate interaction (Table 24, Figure 40). This provided
more evidence for the significant result that occurred in the hybrid spruce seedlings
that received the teabag treatment at the low rate of application (Figure 40).

Figure 40: The height to diameter ratio (HDR) of the pine and spruce seedlings treated with
placement x rate compared to the Controls (no ash and Tb-Only).

95

Discussion
The field trial results suggest the response to ash will largely depend on the
species of conifer seedling targeted for ash fertilization. Aside from species being an
important factor, the rate of application, the placement of the ash, and type of ash
may impact the growth of the target species. Nitrogen, a nutrient often deficient in
B.C. Central Interior forests (Brockley, 1996), was certainly a factor in determining
the effect of ash treatments on both species, but it did not produce the growth
enhancement that was expected. The analysis of the controls alone demonstrated
increased growth in seedlings that did not receive the nitrogen additive at this
particular SBS- Willow site. Generally, the hybrid spruce capitalized the most from
ash addition while lodgepole pine did not respond as well as predicted, especially
when compared to the pine controls. The only ash treatment that initiated a notable
growth response was the UNBC ash, without nitrogen, administered to the hybrid
spruce seedlings.
By comparing two tree species we were able to examine the different
responses from seedlings with contrasting resource preferences. However, it should
be noted that lodgepole pine typically occurs on the drier sites of the Willow variant
(DeLong et al., 2003), and the field site may have been outside of the ideal range for
lodgepole pine. Although pine can respond favourably to nitrogen addition,
particularly at the rate administered in the trial (200kg N ha-1), the responses can be
quite variable in the SBS zone (Brockley, 1996). Also, the response of lodgepole
pine to N fertilization can be affected by other nutrient deficiencies, namely SO4 and
boron (Brockley, 1996). Sulphur deficiencies are common in the B.C.’s Interior and

96

can be initiated by nitrogen fertilization (Brockley, 2012). The foliar analysis revealed
that the sulphur contents in the seedlings were adequate, except in the spruce
seedlings treated with ash and nitrogen (Figure 27, page 63). The N fertilization may
have contributed to this deficiency, as pointed out by Brockley (2012; Appendix F).
Another possible reason for this lack of growth could be attributed to the
broadcast spread of the nitrogen. While the dose was targeted for the seedling, it is
possible the competitive species were potentially outcompeting the pine for light and
resources. Some figures throughout the Methods and Material section give an
impression of the competitive species near the sample seedlings. Although pine is
known to take up nitrogen quite readily (Brockley, 1996), the adjacent plant species
may have been better suited to the site and, therefore, better equipped to capitalize
from the nitrogen, causing the conifer to miss out on the benefits. In reality,
lodgepole pine was not necessarily a designated species for the reforestation of this
particular SBSwk1 site, and the rest of Block 26, outside of the field trial area, was
planted with hybrid spruce. Further, the variation in the planting quality for the
lodgepole pine seedlings may have contributed to seedling growth response,
survival and mortality. For comparison, the mortality of lodgepole pine was 14.9%
(51 of 342 Pl) compared to the hybrid spruce, which was 1.7% (6 of 342 Sx).
The shade-tolerant hybrid spruce seemed to benefit from the ash application,
with and without nitrogen. A species indicatively better suited for this SBSwk1 Willow
site, the hybrid spruce seedlings gained height with the UNBC ash, without the N
added, and increased in diameter with the CPLP x nitrogen treatment. The spruce
also responded to the placement and the rate factors, though not as separate
factors, but as an interaction (placement x rate). Examining two contrasting
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application methods allowed us to use an approach dispersing a large quantity of
ash, and another that employed a localized dosage placed closer to the root plug.
While the former is a typical method of dispersing ash, the latter is a fertilization
method already employed in forestry. These two kinds of ash placements were
integrated into the study to determine whether the location of the ash would impact
the seedlings during a vital establishment phase, particularly where a slump in
nutrients can occur post-harvest (Olsson et al., 1996; Thiffault et al., 2010)
Depending on the mineral content and texture of the ash, UNBC ash being finetextured compared to the chunkier CPLP ash, a type of ash stabilization prior to land
application might be recommended (Jacobson, 2003). The ashes used in this study
were very similar to the gasifier (UNBC) and boiler (CPLP) ashes reported by Domes
et al. (2018). The gasifier ash is a high mineral, low carbon ash with a greater
calcium carbonate equivalence (i.e. greater neutralizing capacity) and base cation
content than the high carbon (mainly charcoal) boiler ash (CPLP). Domes et al.
(2018) found that the low carbon gasifier ash was more reactive, increasing soil pH
and exchangeable base cations than the higher carbon boiler ash.
The teabag method of ash placement, though somewhat more labourintensive, acts as a type of pre-application stabilization, due to the fact it was altered
from its original form. Essentially the ash (or its dissolved constituents) has to be
filtered through a thin paper barrier, and water, or soil moisture, would be the limiting
factor to the dispersal rate of ash nutrients and base cations. Interestingly, the
teabag placement seemed to promote the greatest growth in the hybrid spruce
seedlings, but only where the dose of ash was low. Staples and Van Rees (2001)
recommended low application rates for spruce seedlings (white spruce was used in
98

their study), which appeared to be the case in our trial as well. Also, these ashes are
quite alkaline and can have a relatively high electrical conductivity (see Appendix C),
which is an attribute of fertilization that can inhibit root development (Jacobs &
Timmer, 2005).
The method of application would also determine the manner in which ash
interacted with other ground vegetation, especially when spread via broadcast
application. Not only is it possible that these species intercepted the nitrogen
fertilizer intended for the target conifer seedlings, but also some ground species are
liable to be negatively impacted by ash application (Hart, 2016). With the teabag
method, the ash essentially bypassed the ground species and would be bringing the
ash closer to the seedling’s root system. While the ash teabag could potentially avert
injury to ground vegetation, a dieback of competing vegetation occurring as a result
of broadcast ash application, could be an unintended advantage to utilizing
bioenergy ash. Because manual brushing or mechanical site preparation is usually
coupled with a fertilization treatment, the ash could assist the target conifer species,
but indirectly. However, more in-depth research would be needed to determine
whether ash-induced dieback would be an alternative to a brushing treatment.
The field study allowed us to examine bioenergy ash application on a larger
scale in space and in length of time. Even so, while the initial years of a seedling’s
life cycle may not amount to a large portion of its entire life, the first two seasons of a
seedling’s establishment are crucial in determining the success of reforestation. This
trial also introduced the complexity and randomness that is typical of any research
trial occurring in “natural” field conditions. Wildlife and weather conditions were just

99

some of the unpredictable factors that contributed to the staggering of seedling
planting and treatment placement.
Future research could explore whether site preparation or brushing could
assist in improving the effectiveness of ash fertilization. Other studies could look at
combining broadcast and teabag applications. For example, unprocessed broadcast
ash could act as a fast-release fertilizer and could quickly benefit the seedlings.
Meanwhile, the ash teabag placed underground could supplement some of the lost
biomass contributions from the former forest stand. Due to the contained nature of
the ash in the teabag, it would represent a slow-release fertilizer, benefiting the
seedling some time in the future. Placing the teabag in the same hole may have
encouraged the seedlings to extend roots deeper. More research would be needed
to determine what distance from the seedling’s roots would be the most beneficial
and least likely to cause injury to the seedling. The life span of a teabag buried in soil
and also the migration of the ash solution within the soil would also need further
investigation.
Finally, more studies are needed to determine what sites are ideal candidates
for ash application and which seedling stock is best suited to receive ash fertilizer.
Recommendations for ash application of seedlings in the Central Interior of B.C.
include ensuring the soil at the site has a low base saturation, and if possible
determine whether other soil deficiencies exist, such as nitrogen, boron or sulphur.
Nitrogen may not have been required in the field trial because it did not seem to
benefit either species, especially with respect to the pine, which seemed to receive
the N quite readily in the seedling pot trial. If deficiencies exist, consider the
elemental levels of the ash intended for application and whether adding supplements
100

would be suitable, for the site and in practice. Also, if the ash is primarily made up of
fine minerals similar to the UNBC ash, and is prone to high levels of dust during
application, consider a pre-treatment or stabilization of the ash into a pelleted form or
into teabags. These forms will not only lessen the reactivity and solubility of the ash,
but it would also help to minimize risk to workers tasked with the ash application.

101

Chapter 4 General discussion and final conclusions
The ultimate goal of this study was to pursue innovative ways of using
bioenergy ash in local forests. By determining the effectiveness of ash as a fertilizer
for conifer seedlings, and by integrating information from other countries and current
practices within the Canadian forest industry, it is possible that ash fertilization could
easily be adopted in B.C., and further afield. Forest fertilization has been practiced in
B.C. for many decades but with varying results; this might explain the apprehension
of many forest managers and planners to adopt the practice and reach a consensus
on whether it is worth the investment. Therefore, trying to encourage ash application
in forestry, by either incorporating it as an addition or as a substitute to artificial
fertilizers, may not happen readily. However, considering the escalating issue with
ash accumulating in stockpiles and landfills, it would be practical to decide a course
of action as soon as possible. Incorporating new practices into forest management
should be encouraged as knowledge becomes available, and trying new
approaches, such as ash fertilization, will help add to the appeal of renewable
energy production, which is the ultimate goal to offsetting and divesting from fossil
fuel use.
In this study, the aim was to determine what factors would influence the
seedling growth response to bioenergy ash application. At the onset of this thesis,
three research questions were posed and have been revisited:
Did the species of seedling influence the seedling’s growth response to
bioenergy ash application in conifers planted in the SBSwk1 BEC zone?

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Species was predictably a significant factor in the response to the ash
combinations. In both trials, the site conditions tended to favour one particular
species, and for that particular species, the ash application was optimized. For
instance, the lodgepole pine, a hardy seral species able to endure dry conditions,
benefited from the ash x nitrogen at the EFL compound pot study, where conditions
were exposed and generally a lot of access to light. In contrast the lodgepole pine
did not seem to gain as much in height from the ash addition in the rich field site,
where competitive vegetation may have shaded out the pine seedlings. In contrast,
the hybrid spruce, the preferred species in the Willow variant, which exhibited little
height growth in the seedling pot trial, otherwise thrived in the field site. Perhaps the
longer study period of the field trial, or the extra growing time, benefited the
establishment of the hybrid spruce, which in fact had sufficient levels of N in the
foliage tested from the seedling pot (Appendix E).
Did the ash type influence seedling growth and will nitrogen addition
enhance the growth response?
The influence of ash type alone, and with nitrogen, varied across both trials.
For the aboveground variables, UNBC ash x nitrogen positively impacted the final
median height of the lodgepole pine in the seedling pot trial, but only slightly in the
field trial. The UNBC ash enhanced the height and growth increment of the spruce
seedlings in the field as well, with the non-N samples having the greatest increase.
Contrarily, the CPLP ash and N was beneficial for the final median RCD of the
spruce in the seedling pot trial, and also produced the lowest height-to-diameter ratio
for the pine. Due to the variability amongst results, it was difficult to infer which ash
type or combination acted as the best fertilizer for the seedlings. By examining the
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characterization of the ash, the UNBC ash, which induced the most immediate
growth response, had a higher pH and mineral content compared to the CPLP ash.
Also the CPLP ash, which contained higher amounts of carbon (Appendix C), may
have been less soluble than the fine-textured UNBC ash. The chemical breakdown
of char can take a long time and, therefore, if there were any benefits to growth
attributed to the CPLP ash, they may come later on in the life of the seedling,
requiring further research. Finally, the UNBC ash induced the greatest soil pH
increase for both species of seedling (Figure 29, page 67), adding to the argument
that the UNBC ash was the more reactive ash between the ash types.
Did the method of ash application and the rate of application impact the
growth response of the conifer seedling?
The outcomes allowed us to see that, aside from species, ash and nitrogen
being important drivers, placement method and application rate were actually
significant as well. These two factors became more significant over a longer period
of time, such as the length of the field trial. Despite being limited to the RCD metric
in the field trial, in the seedling pot trial, belowground variables (RCD, RCD growth
and root mass) were all influenced by the placement of the ash. The teabag method
seemed to be preferred by the spruce in both trials. The teabags also decreased the
root-to-shoot ratio for the lodgepole pine planted in pots (Figure 19), which implies
the seedling is responding to favourable growing conditions (Harris, 1992).
Conversely, the broadcast method induced a notable increase in the root mass of
the pine samples in pots. It also stimulated the greatest increase in soil pH,
compared to the Tb application method (Figure 30, page 67). With regard to the rate
of application, judging by the results of both trials, we could infer that the low
104

application rate (2 tonnes ha-1) was the preferred amount for the spruce, particularly
where the teabag method was used (Fig. 14 and 39). The pine RCD growth was
mostly responsive to the low rate as well.
Conclusion
The two trials examined just some of the many factors that should be
considered when coordinating a successful fertilization using ash in sub-boreal
forests. It is important to note that some of the variability presented in this study is
representative of the many inconsistencies that exist between sites, ashes and plant
responses. By referring to the edatopic grid (Appendix G), it is apparent that even
the differences within the Willow variant alone (e.g. soil nutrient and moisture
regimes) make it difficult to predict similar results in a different site series. For
instance the pine in the field trial did not benefit greatly from the ash addition as it did
in the seedling pot trial, but perhaps a site series with a higher soil moisture would
induce a more positive response for the pine in the field. The hybrid spruce, which
was a far more suitable species for the field trial, was able to deliver better
information with a longer study period, compared to the short-term pot study. Not
only was the low rate (2 tonnes ha-1) the preferred rate for the spruce, but also the
teabag application, even exclusive of ash, promoted growth in the height of the
spruce. Emulating the teabag method of application for ash fertilization proved to be
an influential factor in the belowground growth response in the seedling pot trial and
also for spruce in the field trial. However, if the goal is to raise the soil pH from acidic
to more neutral, the broadcast spread of the ash was more appropriate. Also, the
UNBC ash prompted the most growth in the spruce especially, and also the pine.

105

It is important to consider the needs of the site prior to prescribing elemental
supplements to add alongside the ash. Supplementing nitrogen or sulphur for
example, could improve the performance of ash as a fertilizer. This should only be
considered if the site is indeed a candidate for the addition. As noted by Brockley
(2012), nitrogen can induce a sulphur deficiency, and through foliar analysis, one
can anticipate whether or not adding nitrogen is ideal.
It is evident that implementing ash fertilization in the Central Interior of B.C.,
and elsewhere, will face its challenges. Whether it is a practice that will indeed
become integrated into forestry, it is important to consider the entire supply chain of
wood harvested from our forests, from the time of harvest until the wood becomes
ash through a bioenergy process. The concept that bioenergy is a renewable and
sustainable energy is contradicted when we learn about the ash by-products
destined for the landfill or stockpile. By examining bioenergy ash application in a
controlled setting and in a natural field setting, we were able to delve into some
important aspects of ash utilization in sub-boreal forests. Returning ash to its source,
or rather the forest from which the feedstock fiber originated, completes the cycle of
nutrients, which is a necessity for ecosystem health.

106

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Appendices
Appendix A: List of treatments used in both trials
Species

Treatment

1

Sx reps
Pot/Field
5/18

Pl reps
Pot/Field
5/18

Ash type*

Placement**

Rate***

Nitrogen

Control

n/a

n/a

n/a

Control; Cont

2

5/18

5/18

CPLP

Bc

Low

no N

CPLP/Bc/L/noN

3

5/18

5/18

CPLP

Bc

High

no N

CPLP/Bc/H/noN

4

5/18

5/18

CPLP

Bc

Low

with N

CPLP/Bc/L/N

5

5/18

5/18

CPLP

Bc

High

with N

CPLP/Bc/H/N

6

5/18

5/18

UNBC

Bc

Low

no N

UNBC/Bc/L/noN

7

5/18

5/18

UNBC

Bc

High

no N

UNBC/Bc/H/noN

8

5/18

5/18

UNBC

Bc

Low

with N

UNBC/Bc/L/N

9

5/18

5/18

UNBC

Bc

High

with N

UNBC/Bc/H/N

10

5/18

5/18

CPLP

Tb

Low

no N

CPLP/Tb/L/noN

11

5/18

5/18

CPLP

Tb

High

no N

CPLP/Tb/H/noN

12

5/18

5/18

CPLP

Tb

Low

with N

CPLP/Tb/L/N

13

5/18

5/18

CPLP

Tb

High

with N

CPLP/Tb/H/N

14

5/18

5/18

UNBC

Tb

Low

no N

UNBC/Tb/L/noN

15

5/18

5/18

UNBC

Tb

High

no N

UNBC/Tb/H/noN

16

5/18

5/18

UNBC

Tb

Low

with N

UNBC/Tb/L/N

17

5/18

5/18

UNBC

Tb

High

with N

UNBC/Tb/H/N

18

5/18

5/18

Tb

n/a

no N

Tb- Only

19

5/18

5/18

Teabag
2
Only
3
N Only

n/a

n/a

with N

N- Only

95/342

95/342

1

Short Hand

* UNBC = University of British Columbia, CPLP = Canfor
** Bc = Broadcast, Tb = Teabag
*** Low = 2 tonnes ha-1, High = 4 tonnes ha-1
1

no ash, no nitrogen
no ash, no nitrogen
3
no ash, with nitrogen
2

114

Appendix B
Overview map of Blocks 25 and 26

556500

557000

L45514

2
SL-SiCL

B

5993000

556000

5993000

555500

SL
0%

LS
0%

LS
0%

SiL
5%

R5
S3

W
D

S
0%

NCD

12
S
0%

Res. C

Res. A

Blk. 25

NC
D

WD

5992500

D
W

WD

5992500

R5
S3

Res. B

D
NC

LS

S
0%

S
10%
4

WD fSL

Blk. 26
SiL
0%

R3
S4

C 0%

5992000

D
W SL

LS
0%

SiL
10%

NC
D

5992000

fSL
0%

5
SiL
o%

C

3
SiL
5%

R4
S4

LS
0%

R
S4 3

A

Res. A

D
W
Res.
LS
0%

SiL
0%

SiL
0%

C

93J.010

WD

R3 4
S

C

A

SiL
0%

WD

LS
0%

1
fSL
0%

SiL
0%

SiL
0%

SL
5%

A

SiCL
0%

LS
0%

SiL
0%

Res. C

SiL
0%

S
0%

D

fSL
0%

5991000

D
7
SiCL
5%

Res. D

555500
A B

C

SiCL
0%

SiCL
5%

R1
W1

A

556000
D

5991500

SiL
0%

Res. B
LS
0%

5991000

5991500

log
culvert
R2
S4

556500

557000

E

1

Eco Labels

2

A- 0810

3

B- 0710
C- 0910
4

D- 065 095

5

1 centimeter = 100 meters

6

0 50 100

7

200

300

400
Meters

Scale 1:10,000

Ecotype Map
Highway
Forest Service Road
Road Permit Road
Non-tenured Road
Trail

Stream
Indefinite Stream
Wet Draw
R1
W3

Permanent
Located Road Temporary

800

Proposed Road
Skid Trail
Index Contour
Intermediate Contour
Cliff
Dropoff

795
800

Lake

Reach ID/Riparian Class

Bridge

Reach Break
Type Line

Culvert

Mean Water Level
Spot Height
Located Boundary
Reserve/WTP
Adjacent Boundary

Drawn By: HPR
Drawing: 26-ECO

Swamp

J1
SiL
0%

Plot Location
Sample Number
Soil Texture
Coarse Fragments

Date Drawn: 2012/08/13
Date Plotted: 2012/10/11

Tenure: L45514
Block.: 26
Location: Beaver-Bear
BCGS: 93J 010
Forest Inv. Zone: I
Forest District: P.G.
PSYU: Purden

Fieldwork by:

Mapping by:

S M Forrest & Associates Ltd
Suite 100-466 2nd Ave
Prince George, BC
V2L 2Z7

1541 Ogilvie Street
Prince Georg e, BC
V2N 1W7

115

Overview map of field trial site in Block 26

0

25

Paved

Gilbert

Meters

1:2,000
100

Planting Trial
Block 26

50

ALRF Harvested Areas

NP / Roads

WTP; WTR

Standard Units

ALRF Block Boundaries

BC Parks

Research Forest Boundary

Sx

Pli

Planting Trial

Roads

Gravel
Unsurfaced
Non-maintained

150

Drawn by CC: 7/9/2014

556200

556200

26
(

556300

0.6516

556300

0.6102

0.354

0.6786

0.4785

0.3593

556400

556400

556500

556500

556600

556600

556700

¹

556700

Coordinate System: NAD 1983 UTM Zone 10N
Projection: Transverse Mercator
Datum: North American 1983
false easting: 500,000.0000
false northing: 0.0000
central meridian: -123.0000
scale factor: 0.9996
latitude of origin: 0.0000
Units: Meter

5991900

5991800

5991700

5991600

5991500

5991900
5991800
5991700
5991600
5991500

116

Appendix C: Chemical properties of ash types
Table 1: The means (with standard deviations in parentheses) for the chemical
properties and elemental analysis for all three ash types.
Analyte

UNBC Ash
n=3
11.9 (0.127)

CPLP ash #1
n=3
11.1 (0.063)

CPLP Ash #2
n=3
10.4 (0.1)

CaCO3 Equivalent (%)

46.3 (1.33)

28.3 (0.345)

44.6 (1.4)

EC (mS/cm, 1:5)

10.1 (0.445)

5.56 (0.140)

9.1 (0.3)

0.13 (na)

32.5 (na)

58.8 (1.6)

Inorganic C (%)

1.89 (0.950)

3.28 (0.338)

2.8 (0.3)

Total C (%)

6.65 (0.480)

58.8 (2.62)

50.5 (2.6)

Total N (%)

0.037 (0.001)

0.165 (0.003)

0.2 (0.001)

Total S (%)

0.190 (0.008)

0.371 (0.006)

0.5 (0.05)

NO3 (mg N/kg)

na

na

97.8 (4.4)

NH4 (mg N/kg)

na

na

4.8 (1.02)

23990 (1356)

7675 (215)

4470 (404)

pH (in water, 1:2)

Moisture content (%)

Available N

Extractable elements 1
Al (mg/kg)
As (mg/kg)

< 1.0 (na)

< 1.0 (na)

< 4.0 (na)

B (mg/kg)

212.3 (13.60)

145.0 (18.27)

142.6 (8.4)

Ca (%)

18.65 (1.111)

9.758 (0.062)

14.4 (0.6)

Cd (mg/kg)

2.635 (0.045)

5.103 (0.037)

14.1 (1.6)

Co (mg/kg)

23.22 (3.257)

19.71 (1.490)

3.8 (0.9)

Cr (mg/kg)

30.57 (1.006)

13.20 (0.589)

10.6 (1.5)

Cu (mg/kg)

81.50 (3.729)

46.40 (4.731)

52.2 (3.6)

Fe (mg/kg)

18320 (1152.0)

6583 (277.4)

2993 (353.7)

Hg (mg/kg)

2.4 (1.9)

1.5 (0.13)

< 2.0 (na)

K (%)

5.1 (0.26)

2.7 (0.03)

3.2 (0.03)

Mg (%)

2.7 (0.13)

1.1 (0.01)

1.2 (0.1)

Mn (mg/kg)

11330 (666.9)

6165 (53.5)

6422 (317.9)

Mo (mg/kg)

6.4 (0.40)

2.2 (0.50)

4.6 (0.7)

Na (mg/kg)

7226 (390.0)

2884 (65.5)

2503 (33.2)

Ni (mg/kg)

55.8 (1.48)

18.3 (0.704)

13.1 (1.4)

P (%)

0.8 (0.05)

0.5 (0.01)

0.6 (0.04)

Pb (mg/kg)

< 0.4 (na)

< 0.4 (na)

2.6 (0.4)

S (%)

0.2 (0.01)

0.4 (0.01)

0.7 (0.1)

Se (mg/kg)

< 7.0 (na)

< 7.0 (na)

< 2.0 (na)

Zn (mg/kg)

470.6 (18.7)

641.2 (16.2)

1206 (62.9)

117

Continued from previous table.
Analyte

UNBC Ash
n=3

CPLP ash #1
n=3

CPLP Ash #2
n=3

Al (mg/kg)

42540 (1249)

14680 (84.3)

1602.5 (160.5)

B (mg/kg)

na

na

72.2 (5.9)

Ca (mg/kg)

5

2.071 x 10 (1393.0)

5

1.071 x 10 (1597.0)

8.289 x 10 (5450.0)

Cu (mg/kg)

85.8 (3.5)

39.5 (1.1)

31.9 (3.5)

Fe (mg/kg)

2215 (1252)

7864 (299.0)

865.9 (61.7)

K (mg/kg)

65270 (2152)

29980 (248.8)

26360 (1505)

Mg (mg/kg)

31790 (1415)

11870 (96.9)

8986 (798.3)

Mn (mg/kg)

12250 (814.7)

6534 (95.0)

5140 (424.7)

Na (mg/kg)

14030 (595.4)

5642 (179.5)

1873 (93.4)

P (mg/kg)

9328 (650.0)

5804 (76.9)

1759 (54.3)

S (mg/kg)

2079 (134.2)

3946 (94.1)

3852 (438.2)

Zn (mg/kg)

460.0 (12.2)

632.7 (7.5)

1200 (85.9)

Extractable elements 2

4

Notes:
CPLP #1 was collected from PG Pulp Boiler #2 on April 27, 2012; this ash was used
in the seedling pot study
CPLP #2 was collected from PG Pulp Boiler #2 on January 10, 2013; this ash was
used in the seedling field study
Extractable Elements 1 represent elemental concentrations via ICP-OES following
US EPA extraction method 3051A: concentrated HNO3 and HCl; elemental
concentrations are more typically reported in the literature using this method than
those using method 3052
Extractable Elements 2 represent elemental concentrations via ICP-OES following
US EPA extraction method 3052: concentrated HNO3, HF and H3BO3; method 3052
is considered to be a more complete digestion as aluminosilicate minerals are
dissolved, unlike method 3051A which does not dissolve aluminosilicates

118

Appendix D: Calculations for ash application rate
Note: While the low rate is referred to as 2 tonnes ha-1 and the high rate as 4 tonnes
ha-1, the actual amounts were based on the surface area (A) of the pot from the
seedling pot study.
The formula used to determine the equivalent amounts for both ash types, based on
the mineral weight and the area of the pot:
Equation 1
X g of ash = [A x (rate of application)] x (1 + ω)
- where X is the amount of ash, A is the area of the pot and ω is the gravimetric
moisture content of the ash
The calculation using the above formula to determine the CPLP and the UNBC ash
amounts for the low rate (2 tonnes ha-1). The high rate (4 tonnes ha-1) was equal to
two doses of the low rate (i.e. one teabag = low rate, two teabags = high rate):
Sample equation for CPLP ash:
X g of ash = [A x (rate of application)] x (1 + ω)
= [0.000 001 767 ha x 2 000 000 g/ha] x (1+ 0.7589 ω CPLP ash g/g dry weight)
= 3.534 (1.7589)
= 6.216g CPLP ash (for low rate, 12.43g for high rate)
Sample equation for the UNBC ash:
X g of ash = [A x (rate of application)] x (1 + ω)
= [0.000 001 767 ha x 2 000 000 g/ha] x (1+ 0.0013 ω UNBC ash g/g dry weight)
= 3.534 (1.0013)
= 3.539g UNBC ash (for low rate, 7.077g for high rate)

119

Appendix E: Foliar analysis

Analysis performed by the Ministry of Environment, Environmental Sustainability and Strategic Policy
Division (In date: 2015/09/22, out date 2015/10/22). Asterisk (*) signifies data (i.e. N and S values)
that has been normalized according to the spreadsheet provided by Brockley 2012.
Sp.
1 Pl
2 Pl
3 Pl
4 Pl
5 Pl
6 Pl
7 Pl
8 Pl
9 Pl
10 Pl
11 Pl
12 Pl
13 Pl
14 Pl
15 Pl
16 Pl
17 Pl
18 Pl
19 Pl
20 Sx
21 Sx
22 Sx
23 Sx
24 Sx
25 Sx
26 Sx
27 Sx
28 Sx
29 Sx
30 Sx
31 Sx
32 Sx
33 Sx
34 Sx
35 Sx
36 Sx
37 Sx
38 Sx

Cont
Cont
Cont
CPLP
CPLP
CPLP
CPLP
CPLP
CPLP
CPLP
CPLP
UNBC
UNBC
UNBC
UNBC
UNBC
UNBC
UNBC
UNBC
Cont
Cont
Cont
CPLP
CPLP
CPLP
CPLP
CPLP
CPLP
CPLP
CPLP
UNBC
UNBC
UNBC
UNBC
UNBC
UNBC
UNBC
UNBC

ash
Cont
Cont
Tb
Bc
Bc
Bc
Bc
Tb
Tb
Tb
Tb
Bc
Bc
Bc
Bc
Tb
Tb
Tb
Tb
Cont
Cont
Tb
Bc
Bc
Bc
Bc
Tb
Tb
Tb
Tb
Bc
Bc
Bc
Bc
Tb
Tb
Tb
Tb

place
Cont
Cont
Cont
H
H
L
L
H
H
L
L
H
H
L
L
H
H
L
L
Cont
Cont
Cont
H
H
L
L
H
H
L
L
H
H
L
L
H
H
L
L

rate
no N
yes N
no N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N

N

N (%)
1.15
1.06
1.33
1.13
1.12
1.00
1.23
1.16
1.22
1.05
1.19
1.40
1.33
0.95
1.11
1.07
1.03
1.23
1.14
0.91
1.36
0.97
0.78
1.46
0.91
1.51
0.93
1.50
0.85
1.53
0.75
1.21
0.92
1.33
0.76
1.32
0.88
1.43

sd
0.33
0.16
0.47
0.35
0.27
0.32
0.17
0.35
0.44
0.25
0.19
0.23
0.20
0.27
0.17
0.32
0.17
0.38
0.19
0.27
0.19
0.22
0.07
0.24
0.28
0.20
0.10
0.18
0.29
0.20
0.08
0.17
0.24
0.23
0.08
0.12
0.19
0.16

Al
(mg/kg)
204.2
84.0
292.9
201.2
96.6
248.5
97.5
179.4
111.0
219.3
110.4
222.1
125.2
167.9
97.6
217.8
100.9
253.0
96.6
92.1
67.7
74.6
44.6
62.3
66.3
62.4
57.2
62.7
86.9
56.3
86.8
64.2
79.0
72.1
53.3
73.1
66.3
65.0

sd2
46.4
12.9
30.8
68.3
26.6
44.3
19.8
54.9
19.7
16.8
50.7
37.6
44.0
27.6
24.8
54.7
26.7
100.3
14.5
45.4
7.0
10.0
8.8
23.9
22.9
9.5
3.6
4.7
85.8
9.4
21.0
10.8
33.9
9.1
6.9
27.4
7.7
6.5

B
(mg/kg)
33.2
17.2
31.1
38.3
25.0
40.0
17.2
46.6
25.3
32.3
19.8
47.5
33.0
34.8
23.8
54.6
29.0
43.0
25.0
48.0
33.1
40.1
38.2
43.3
61.3
39.0
51.6
40.7
45.7
30.2
60.2
38.8
54.9
30.3
60.8
46.7
60.5
48.0

sd3
7.3
3.0
4.4
7.7
4.6
8.5
2.8
10.5
5.3
6.2
3.9
4.3
5.9
4.1
4.1
11.3
4.6
9.1
3.9
12.2
2.5
8.8
8.3
13.2
7.0
5.4
11.9
12.0
4.4
8.9
10.0
8.2
9.0
7.6
13.9
18.6
19.6
13.6

Total C
(%)
52.6
53.2
52.3
52.1
52.9
52.4
53.2
52.0
52.9
52.4
52.7
51.5
52.4
52.0
52.7
52.5
53.3
51.1
53.7
50.1
51.1
49.8
50.5
50.6
50.1
50.4
49.8
50.8
50.0
51.4
49.0
51.3
49.5
51.2
49.5
51.2
49.9
51.0

sd4
0.42
0.44
0.10
0.98
0.51
0.67
0.36
0.50
0.34
0.36
0.46
0.52
0.56
0.41
0.26
0.36
0.43
1.40
0.68
0.47
0.98
0.51
0.42
0.67
1.28
0.58
0.40
0.54
0.48
0.26
0.27
0.22
0.79
1.03
0.44
0.90
0.65
0.47

Cu
(mg/kg)
3.96
3.74
4.47
3.66
3.50
3.31
3.76
3.46
3.51
3.59
3.65
3.92
3.62
3.43
3.45
3.65
3.32
4.38
3.65
4.07
4.48
4.01
3.45
4.46
4.16
4.99
3.12
4.45
3.12
4.65
4.82
4.41
3.70
4.67
3.28
4.49
3.62
4.52

sd5
1.42
0.58
0.74
0.27
0.80
0.86
0.55
0.77
0.71
0.20
0.43
0.40
0.71
0.34
0.43
0.64
0.54
1.25
0.29
1.14
0.10
0.71
1.14
0.86
1.02
0.63
0.16
0.61
1.36
0.65
1.02
0.33
0.67
0.57
0.36
0.80
0.66
0.61

Fe
(mg/kg)
71.2
51.6
69.4
80.6
71.6
70.5
73.2
66.7
64.8
75.7
70.2
86.4
72.5
75.3
69.7
84.0
58.1
102.4
58.7
93.7
71.4
87.9
59.4
85.8
96.9
90.2
64.1
71.8
112.7
69.1
90.9
71.0
93.7
78.4
59.3
81.8
71.1
83.4

sd6
23.3
4.8
5.7
8.6
7.1
7.6
6.1
3.0
5.8
10.0
18.6
16.1
19.0
11.8
12.2
17.6
13.0
62.5
4.8
48.5
2.7
13.5
11.9
33.6
50.9
9.8
7.7
11.0
104.3
14.7
26.8
12.0
46.7
16.9
10.6
32.6
13.0
12.6

Mg (%)
0.160
0.142
0.164
0.152
0.137
0.169
0.113
0.183
0.120
0.157
0.133
0.177
0.161
0.168
0.134
0.172
0.119
0.149
0.106
0.167
0.112
0.186
0.178
0.137
0.249
0.195
0.170
0.131
0.205
0.147
0.221
0.110
0.176
0.143
0.187
0.150
0.184
0.160

sd7
0.02
0.02
0.04
0.02
0.03
0.02
0.00
0.02
0.03
0.00
0.01
0.02
0.03
0.04
0.01
0.02
0.02
0.04
0.01
0.03
0.06
0.05
0.03
0.01
0.03
0.04
0.05
0.04
0.07
0.02
0.03
0.02
0.03
0.04
0.05
0.06
0.06
0.04

Mn
(mg/kg)
627.0
309.0
767.8
628.6
324.4
597.9
314.8
617.5
332.4
573.6
316.5
684.3
398.7
372.3
311.9
504.5
271.6
621.5
292.4
595.6
712.5
643.5
446.3
857.7
466.6
909.9
682.0
926.6
608.9
653.9
433.3
605.8
438.2
651.7
461.8
724.8
589.8
759.3

sd8
211.7
68.3
314.3
283.4
94.7
125.6
81.0
282.6
101.0
101.7
107.8
193.2
104.1
124.9
128.0
54.4
65.7
386.5
37.5
223.1
280.6
134.2
182.7
325.9
33.3
198.5
110.9
385.7
233.7
205.3
120.1
137.6
126.1
149.7
53.9
93.4
180.0
248.7

Na
(mg/kg)
3.7
8.2
7.7
2.8
10.4
6.2
4.7
6.6
5.3
4.3
8.2
4.3
4.7
0.3
2.8
5.2
10.1
6.2
5.0
18.4
13.8
16.4
7.8
28.3
8.5
11.3
7.3
9.2
10.3
11.2
16.7
80.8
38.1
15.1
13.1
24.2
10.9
14.9

sd9

1.9
7.2
4.3
4.7
6.8
10.1
4.6
6.9
4.0
3.9
6.0
5.1
4.6
0.6
2.4
2.0
7.3
7.4
3.5
2.3
3.2
7.1
2.5
41.9
1.3
5.1
4.8
5.0
6.7
5.4
13.0
132.0
51.6
7.7
3.2
13.9
4.2
6.7

P (%)

0.118
0.096
0.136
0.117
0.092
0.116
0.093
0.117
0.100
0.111
0.100
0.147
0.103
0.117
0.098
0.122
0.091
0.124
0.083
0.127
0.112
0.148
0.116
0.115
0.141
0.117
0.116
0.109
0.130
0.110
0.139
0.101
0.125
0.105
0.130
0.111
0.120
0.128

sd10

0.02
0.01
0.02
0.02
0.01
0.02
0.02
0.02
0.01
0.02
0.01
0.02
0.02
0.02
0.01
0.00
0.01
0.03
0.01
0.02
0.03
0.02
0.02
0.03
0.03
0.01
0.01
0.02
0.03
0.03
0.02
0.01
0.02
0.01
0.02
0.01
0.01
0.01

Zn
(mg/kg)

77.6
45.1
74.7
86.6
51.8
71.5
43.4
68.4
48.3
61.5
43.6
75.1
55.6
72.9
43.7
67.1
47.6
77.1
42.9
77.3
26.7
91.9
58.7
36.1
74.2
42.4
59.3
37.7
88.6
40.9
47.1
35.3
54.8
47.1
68.8
38.3
76.9
53.3

sd11

24.9
9.3
5.4
22.1
17.9
22.0
6.6
18.0
16.9
20.2
14.2
7.5
8.1
3.6
5.1
3.4
16.1
33.7
7.7
29.5
10.1
12.4
17.4
17.4
31.8
15.4
16.0
17.4
40.2
22.6
13.9
15.7
27.1
32.1
20.5
13.7
18.6
26.7

120

Continued from the previous table.

Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx

Sp.
Cont
Cont
Cont
CPLP
CPLP
CPLP
CPLP
CPLP
CPLP
CPLP
CPLP
UNBC
UNBC
UNBC
UNBC
UNBC
UNBC
UNBC
UNBC
Cont
Cont
Cont
CPLP
CPLP
CPLP
CPLP
CPLP
CPLP
CPLP
CPLP
UNBC
UNBC
UNBC
UNBC
UNBC
UNBC
UNBC
UNBC

ash
Cont
Cont
Tb
Bc
Bc
Bc
Bc
Tb
Tb
Tb
Tb
Bc
Bc
Bc
Bc
Tb
Tb
Tb
Tb
Cont
Cont
Tb
Bc
Bc
Bc
Bc
Tb
Tb
Tb
Tb
Bc
Bc
Bc
Bc
Tb
Tb
Tb
Tb

place
Cont
Cont
Cont
H
H
L
L
H
H
L
L
H
H
L
L
H
H
L
L
Cont
Cont
Cont
H
H
L
L
H
H
L
L
H
H
L
L
H
H
L
L

rate
no N
yes N
no N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N

N

Ca (%)
0.325
0.371
0.322
0.386
0.451
0.345
0.358
0.302
0.345
0.344
0.356
0.418
0.466
0.370
0.372
0.350
0.373
0.353
0.336
0.648
0.838
0.753
0.584
0.980
0.838
1.045
0.676
0.968
0.711
0.880
0.678
0.807
0.776
0.838
0.634
0.922
0.734
0.944

sd
0.03
0.07
0.02
0.03
0.06
0.08
0.08
0.05
0.09
0.08
0.07
0.08
0.05
0.07
0.08
0.02
0.07
0.06
0.03
0.15
0.08
0.08
0.12
0.20
0.04
0.18
0.08
0.22
0.31
0.24
0.24
0.09
0.09
0.19
0.07
0.26
0.26
0.17

K (%)
0.417
0.276
0.520
0.479
0.370
0.447
0.328
0.481
0.397
0.469
0.346
0.514
0.313
0.481
0.318
0.502
0.327
0.473
0.319
0.462
0.420
0.544
0.419
0.394
0.477
0.378
0.430
0.374
0.469
0.376
0.441
0.387
0.519
0.342
0.542
0.394
0.423
0.403

sd2
0.05
0.04
0.06
0.09
0.04
0.03
0.08
0.10
0.05
0.11
0.04
0.08
0.02
0.04
0.07
0.05
0.03
0.09
0.08
0.04
0.02
0.03
0.03
0.05
0.02
0.06
0.07
0.03
0.06
0.03
0.05
0.03
0.10
0.04
0.10
0.03
0.05
0.07

N (%)*
1.10
1.01
1.27
1.08
1.07
0.95
1.18
1.11
1.16
1.01
1.14
1.34
1.28
0.91
1.06
1.02
0.99
1.18
1.09
0.87
1.30
0.93
0.75
1.40
0.87
1.44
0.89
1.44
0.81
1.46
0.72
1.15
0.88
1.27
0.73
1.26
0.84
1.37

sd3
0.32
0.15
0.45
0.33
0.26
0.31
0.16
0.34
0.42
0.24
0.18
0.22
0.19
0.26
0.16
0.31
0.16
0.37
0.18
0.26
0.18
0.22
0.07
0.23
0.27
0.19
0.09
0.17
0.28
0.19
0.08
0.16
0.23
0.22
0.08
0.11
0.18
0.15

S (%)*
0.129
0.076
0.142
0.140
0.084
0.126
0.074
0.149
0.095
0.126
0.087
0.155
0.085
0.117
0.074
0.156
0.077
0.135
0.079
0.081
0.269
0.065
0.084
0.082
0.114
0.252
0.075
0.085
0.087
0.086
0.088
0.074
0.072
0.076
0.070
0.081
0.072
0.086

sd4
0.022
0.012
0.021
0.027
0.014
0.035
0.014
0.024
0.014
0.012
0.019
0.025
0.015
0.011
0.011
0.014
0.012
0.043
0.011
0.006
0.381
0.009
0.034
0.011
0.040
0.325
0.025
0.013
0.030
0.011
0.013
0.005
0.019
0.011
0.016
0.009
0.013
0.004

Zn
(mg/kg)
77.6
45.1
74.7
86.6
51.8
71.5
43.4
68.4
48.3
61.5
43.6
75.1
55.6
72.9
43.7
67.1
47.6
77.1
42.9
77.3
26.7
91.9
58.7
36.1
74.2
42.4
59.3
37.7
88.6
40.9
47.1
35.3
54.8
47.1
68.8
38.3
76.9
53.3

sd5
24.9
9.3
5.4
22.1
17.9
22.0
6.6
18.0
16.9
20.2
14.2
7.5
8.1
3.6
5.1
3.4
16.1
33.7
7.7
29.5
10.1
12.4
17.4
17.4
31.8
15.4
16.0
17.4
40.2
22.6
13.9
15.7
27.1
32.1
20.5
13.7
18.6
26.7

N:Ca
3.42
2.76
3.99
2.87
2.39
2.75
3.37
3.68
3.39
3.17
3.24
3.36
2.75
2.54
2.90
2.94
2.68
3.29
3.23
1.34
1.56
1.23
1.31
1.44
1.06
1.40
1.33
1.54
1.21
1.72
1.15
1.46
1.12
1.54
1.16
1.45
1.21
1.47

sd6
1.1
0.4
1.5
1.1
0.5
0.6
0.4
0.9
0.7
1.4
0.3
1.2
0.4
0.8
0.3
0.9
0.4
0.6
0.3
0.2
0.2
0.3
0.3
0.2
0.4
0.2
0.2
0.3
0.4
0.3
0.3
0.3
0.2
0.1
0.2
0.5
0.3
0.2

N:S
8.4
13.3
8.7
7.6
12.8
7.6
16.2
7.4
12.2
8.1
13.3
8.7
15.3
7.7
14.4
6.7
12.9
8.8
13.9
10.6
12.8
14.1
9.5
17.1
7.7
13.2
12.8
17.0
10.2
17.0
8.5
15.6
12.6
16.7
10.8
15.7
11.8
15.9

sd7
1.3
0.4
2.2
1.1
1.6
1.4
2.1
1.4
3.2
2.1
1.5
0.5
2.3
1.7
1.5
2.5
0.8
0.8
0.8
2.4
7.5
1.6
2.3
1.1
0.9
7.7
3.4
0.7
4.4
0.3
2.3
2.0
3.4
0.7
2.5
0.7
2.6
1.2

N:M
6.9
7.2
8.4
7.1
8.0
5.6
10.5
6.2
9.5
6.4
8.6
7.6
8.0
5.6
7.9
6.2
8.3
8.1
10.4
5.6
13.6
5.6
4.2
10.3
3.6
7.5
5.7
11.7
4.4
10.2
3.3
11.2
5.0
9.5
4.2
9.1
4.7
8.8

sd8
2.0
1.0
3.9
2.0
1.6
1.7
1.4
2.4
1.4
1.4
0.7
1.4
1.1
2.1
0.6
2.9
1.2
2.1
2.4
2.9
5.3
3.2
0.5
2.2
1.3
1.1
1.8
3.4
2.1
2.6
0.6
4.2
1.2
3.0
1.6
2.8
0.6
1.5

N:P

9.2
10.6
9.2
9.2
11.6
8.2
12.9
9.4
11.5
9.1
11.5
9.2
12.5
7.8
10.9
8.3
10.8
9.5
13.2
6.8
11.9
6.5
6.5
12.3
6.5
12.4
7.7
13.3
6.2
13.8
5.3
11.6
7.3
12.4
5.7
11.4
7.1
10.8

sd9

1.37
1.21
2.47
1.57
1.23
1.47
1.33
1.07
2.54
2.03
0.94
1.71
0.63
1.56
0.72
2.16
0.74
1.60
1.70
1.11
1.27
2.45
0.60
0.96
2.14
1.38
1.13
1.17
1.13
3.09
1.29
1.87
2.76
2.86
1.35
0.27
1.82
1.92

N:K

2.61
3.69
2.51
2.33
2.92
2.15
3.70
2.28
3.05
2.34
3.32
2.62
4.10
1.93
3.44
2.08
3.06
2.48
3.54
1.92
3.12
1.72
1.78
3.57
1.84
3.83
2.12
3.84
1.81
3.90
1.64
3.00
1.76
3.82
1.38
3.20
2.03
3.56

sd10

0.58
0.42
0.99
0.81
0.69
0.76
0.57
0.26
1.46
1.14
0.46
0.29
0.66
0.68
0.85
0.80
0.64
0.48
0.86
0.66
0.56
0.50
0.10
0.60
0.62
0.08
0.48
0.15
0.88
0.54
0.07
0.48
0.65
1.01
0.29
0.12
0.60
1.15

121

Appendix F: Foliar nutrient interpretative criteria
(Brockley, 2012)

Ratio
N:P

N:K

N:Mg

N:S

a

Interpretation
Moderate to severe P deficiency
Slight to moderate P deficiency
Possible slight P deficiency
No P deficiency

Lodgepole
pine
> 13
11 – 13
10 – 11
< 10

Moderate to severe K deficiency
Slight to moderate K deficiency
Possible slight K deficiency
No K deficiency

Threshold value
Interior spruce
Douglas-fir
> 11
10 – 11
9 – 10
<9

> 11
10 – 11
9 – 10
<9

> 4.5
3.5 – 4.5
2.5 – 3.5
< 2.5

> 4.0
3.0 – 4.0
2.0 – 3.0
< 2.0

> 3.5
2.5 – 3.5
2.0 – 2.5
< 2.0

Moderate to severe Mg deficiency
Slight to moderate Mg deficiency
Possible slight Mg deficiency
No Mg deficiency

> 30
20 – 30
15 – 20
< 15

> 30
20 – 30
15 – 20
< 15

> 30
20 – 30
15 – 20
< 15

Severe S deficiency
Moderate to severe S deficiency
Slight to moderate S deficiency
a
No S deficiency

> 25
20 – 25
15 – 20
< 15

> 25
20 – 25
15 – 20
< 15

> 25
20 – 25
15 – 20
< 15

: Sulphur deficiency will likely be induced by N fertilization if N:S > 13

122

Appendix G: Soil properties
Seedling pot soils
Table 1: The means (with standard deviations in parentheses) of soil chemical
properties and elemental analysis.
Parameter
Sand (%)

Soil –no perlite
n=4
13.9 (1.2)

Soil with perlite
n=4
14.9 (0.02)

Silt (%)

69.0 (0.07)

68.6 (1.2)

Clay (%)

17.1 (0.6)

16.4 (1.2)

5.0 (0.005)

4.9 (0.01)

CEC (cmol /kg)

13.9 (0.4)

13.7 (0.2)

Available P (mg/kg)

125.3 (9.8)

124.2 (2.8)

Inorganic C (%)

< 0.07 (na)

0.2 (0.1)

Total C (%)

3.4 (0.1)

3.2 (0.05)

Total N (%)

0.2 (0.01)

0.2 (0.004)

Total S (%)

0.02 (0.002)

0.02 (0.004)

Al (mg/kg)

25190 (548.4)

24380 (814.2)

pH (1:1, Soil:water)
+

As (mg/kg)

< 4 (na)

<4 (na)

B (mg/kg)

5.5 (0.3)

4.7 (0.2)

Ca (%)

0.6 (0.004)

0.6 (0.01)

Cd (mg/kg)

2.9 (0.1)

2.9 (0.1)

Co (mg/kg)

31.1 (2.1)

27.8 (2.5)

Cr (mg/kg)

61.7 (0.5)

60.8 (1.3)

Cu (mg/kg)

19.8 (0.3)

19.7 (0.7)

Fe (mg/kg)

35960 (521.9)

35670 (531.0)

Hg (mg/kg)

< 2 (na)

< 2 (na)

K (%)

0.3 (0.01)

0.3 (0.01)

Mg (%)

0.6 (0.01)

0.6 (0.01)

Mn (mg/kg)

1239 (108.7)

1218 (79.6)

Mo (mg/kg)

0.7 (0.1)

0.7 (0.01)

Na (mg/kg)

435.5 (27.1)

552.4 (27.4)

Ni (mg/kg)

37.7 (0.6)

37.9 (0.7)

P (%)

0.2 (0.004)

0.2 (0.002)

Pb (mg/kg)

6.1 (0.7)

5.6 (0.5)

0.03 (0.001)

0.02 (0.002)

Se (mg/kg)

< 2 (na)

< 2 (na)

Zn (mg/kg)

158.6 (2.5)

155.0 (2.9)

+

0.6 (0.03)

0.6 (0.03)

+

10.7 (0.3)

10.4 (0.1)

S (%)

Exchangeable cations
Al (cmol /kg)
Ca (cmol /kg)

123

+

Fe (cmol /kg)

0.02 (0.02)

0.01 (0.01)

+

K (cmol /kg)

0.4 (0.01)

0.4 (0.01)

+

2.0 (0.1)

2.0 (0.05)

+

0.1 (0.01)

0.1 (0.002)

+

0.1 (0.01)

0.1 (0.004)

Mg (cmol /kg)
Mn (cmol /kg)
Na (cmol /kg)

Field site soils
Table 2: The means (with standard deviations in parentheses) of soil chemical
properties and elemental analysis of the soils from the field trial site.
Parameter
Sand (%)

na

Ae
n=3
39.9 (10.3)

Silt (%)

na

49.6 (7.75)

44.8 (7.77)

Clay (%)

na

10.6 (2.65)

9.90 (2.03)

4.9 (0.31)

4.7 (0.14)

5.1 (0.12)

CEC (cmol /kg)

12.5 (1.03)

4.9 (0.94)

4.9 (0.98)

Available P (mg/kg)

27.2 (11.3)

31.6 (24.6)

77.7 (64.2)

Total C (%)

19.1 (7.29)

1.57 (0.130)

2.34 (0.935)

Total N (%)

0.876 (0.330)

0.112 (0.009)

0.134 (0.047)

Total S (%)

0.089 (0.033)

0.011 (0.002)

0.017 (0.007)

C:N

21.8 (0.350)

14.0 (0.805)

17.3 (0.990)

pH (1:1, soil:water)
+

LFH
n=3

Bm
n=3
45.3 (7.48)

Exchangeable elements 1
Al (mg/kg)

14530 (1764)

20460 (1257)

28460 (5660)

As (mg/kg)

< 2 (na)

< 2 (na)

< 2 (na)

B (mg/kg)

5.37 (0.672)

2.43 (0.228)

< 2 (na)

Ca (%)

0.756 (0.085)

0.446 (0.078)

0.497 (0.055)

Cd (mg/kg)

1.0 (0.3)

< 2 (na)

< 2 (na)

Co (mg/kg)

14.3 (6.0)

24.1 (0.830)

26.8 (6.49)

Cr (mg/kg)

47.9 (7.0)

67.1 (3.08)

75.7 (6.42)

Cu (mg/kg)

8.4 (1.7)

9.07 (1.30)

13.8 (0.889)

Fe (mg/kg)

13700 (4660)

22440 (1530)

3683 (4499)

Hg (mg/kg)

< 1 (na)

< 1 (na)

< 1 (na)

K (%)

0.256 (0.041)

0.292 (0.014)

0.271 (0.030)

Mg (%)

0.205 (0.042)

0.334 (0.048)

0.605 (0.030)

Mn (mg/kg)

< 2 (na)

1694.8 (917.1)

499.4 (86.4)

Mo (mg/kg)

< 2 (na)

< 2 (na)

< 2 (na)

Na (mg/kg)

459.1 (75.7)

544.5 (11.0)

495.5 (12.8)

Ni (mg/kg)

11.5 (1.1)

15.0 (1.4)

36.9 (7.8)

P (%)

0.1 (0.02)

0.07 (0.003)

0.2 (0.03)

124

Pb (mg/kg)

6.6 (0.8)

5.2 (0.1)

2.8 (0.5)

S (%)

0.08 (0.03)

0.01 (0.001)

0.02 (0.01)

Se (mg/kg)

< 4 (na)

< 4 (na)

< 4 (na)

Zn (mg/kg)

9.8 (1.2)

75.3 (23.1)

117.6 (25.2)

Exchangeable elements 2
+

Al (cmol /kg)

0.3 (0.3)

2.2 (0.4)

1.8 (.04)

+

10.1 (1.2)

2.0 (1.1)

2.5 (1.2)

+

0.01 (0.01)

0.04 (0.04)

0.03 (0.01)

Ca (cmol /kg)
Fe (cmol /kg)
+

K (cmol /kg)

0.3 (0.03)

0.1 (0.03)

0.03 (0.02)

+

1.5 (0.2)

0.5 (0.2)

0.5 (0.2)

+

0.3 (0.1)

0.1 (0.1)

0.02 (0.003)

+

0.03 (0.01)

0.03 (0.01)

0.03 (0.01)

Mg (cmol /kg)
Mn (cmol /kg)
Na (cmol /kg)

Notes:
Extractable Elements 1 represent elemental concentrations via ICP-OES following
US EPA extraction method 3051A: concentrated HNO3 and HCl; elemental
concentrations are more typically reported in the literature using this method than
those using method 3052
Extractable Elements 2 represent elemental concentrations via ICP-OES following
US EPA extraction method 3052: concentrated HNO3, HF and H3BO3; method 3052
is considered to be a more complete digestion as aluminosilicate minerals are
dissolved, unlike method 3051A which does not dissolve aluminosilicates

125

Appendix H: Edatopic grid for the SBS wk1 (Willow variant)
(DeLong et al., 2003)

Site Series
01 Sxw- Oak fern
02 Pl – Huckleberry - Cladina
03 Pl – Huckleberry - Velvet-leaved blueberry
04 SxwFd – Knight’s Plume
05 Sxw – Huckleberry – Highbush cranberry
06 Sxw – Pink spirea – Oak fern
07 Sxw - Twinberry – Oak fern
08 Sxw – Devil’s Club
09 Sxw – Horsetail
10 Sxw – Devil’s Club – Lady fern
11SbSxw – Scrub birch – Sedge
12 SbPl- Feathermoss

126

Appendix I: Seedling pot trial data
Table 1: The mean values and standard deviations (sd) for each response variables,
final height, total height growth, final root collar diameter (RCD), total RCD growth
and height to diameter ratio (HDR), root, shoot and total masses for the Enhanced
Forestry Lab seedling pot trial.

#
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38

Sp.
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx

Ash
Cont
Cont
Cont
CPLP
CPLP
CPLP
CPLP
CPLP
CPLP
CPLP
CPLP
UNBC
UNBC
UNBC
UNBC
UNBC
UNBC
UNBC
UNBC
Cont
Cont
Cont
CPLP
CPLP
CPLP
CPLP
CPLP
CPLP
CPLP
CPLP
UNBC
UNBC
UNBC
UNBC
UNBC
UNBC
UNBC
UNBC

Place
Cont
Cont
Tb
Bc
Bc
Bc
Bc
Tb
Tb
Tb
Tb
Bc
Bc
Bc
Bc
Tb
Tb
Tb
Tb
Cont
Cont
Tb
Bc
Bc
Bc
Bc
Tb
Tb
Tb
Tb
Bc
Bc
Bc
Bc
Tb
Tb
Tb
Tb

Rate
Cont
Cont
Cont
H
H
L
L
H
H
L
L
H
H
L
L
H
H
L
L
Cont
Cont
Cont
H
H
L
L
H
H
L
L
H
H
L
L
H
H
L
L

N
no N
yes N
no N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N

Final
height
(cm)
25.9
27.1
26.9
26.9
24.8
26.5
27.9
28.0
27.6
25.7
27.1
25.9
29.4
23.6
30.3
25.3
26.5
27.2
31.6
26.7
27.6
25.7
29.1
26.4
27.3
27.8
27.2
26.6
27.0
25.7
26.5
26.1
26.1
28.5
27.5
27.2
27.6
28.2

sd
3.39
2.79
5.34
4.04
2.70
2.53
5.70
2.45
2.88
3.42
4.88
3.42
6.35
4.42
1.86
2.68
2.80
2.08
2.21
2.59
3.32
2.67
0.92
3.34
3.76
5.84
1.61
2.31
3.26
3.22
3.22
2.88
2.94
2.87
1.97
2.54
2.03
2.29

Final
RCD
(cm)
0.615
0.754
0.600
0.583
0.733
0.606
0.796
0.587
0.744
0.574
0.724
0.564
0.735
0.552
0.786
0.570
0.735
0.575
0.709
0.649
0.825
0.668
0.755
0.863
0.663
0.910
0.729
0.864
0.648
1.004
0.748
0.843
0.725
0.905
0.715
0.885
0.765
0.890

sd
0.063
0.057
0.076
0.032
0.060
0.067
0.076
0.083
0.080
0.050
0.059
0.027
0.080
0.022
0.033
0.082
0.056
0.068
0.081
0.066
0.149
0.053
0.071
0.113
0.058
0.053
0.101
0.105
0.069
0.124
0.118
0.067
0.106
0.038
0.080
0.051
0.071
0.055

Total
growth
(cm)
11.2
13.9
13.7
13.1
11.0
13.5
15.3
13.4
13.3
11.1
13.1
14.4
12.8
9.26
14.5
10.8
13.1
11.9
15.4
7.48
7.00
7.00
6.74
6.96
5.30
6.08
7.80
6.32
6.92
7.18
5.28
7.76
6.50
7.98
7.08
7.08
7.06
7.94

sd
2.70
2.03
3.36
3.27
3.95
1.33
3.11
1.72
1.88
4.92
5.27
3.64
8.31
4.93
3.35
4.74
1.45
4.01
1.48
0.29
1.02
2.23
1.81
2.05
2.57
3.12
0.37
1.43
1.05
1.34
2.69
1.83
1.51
1.26
2.35
2.69
1.07
1.37

Total
RCD
(mm)
0.213
0.330
0.199
0.185
0.313
0.201
0.405
0.177
0.321
0.178
0.324
0.142
0.333
0.127
0.411
0.165
0.331
0.137
0.323
0.235
0.381
0.217
0.266
0.398
0.166
0.433
0.271
0.409
0.217
0.531
0.268
0.372
0.215
0.413
0.245
0.426
0.277
0.481

sd
0.078
0.057
0.084
0.028
0.024
0.074
0.061
0.071
0.053
0.078
0.056
0.060
0.074
0.062
0.046
0.095
0.069
0.058
0.096
0.070
0.069
0.081
0.094
0.097
0.066
0.057
0.099
0.058
0.084
0.083
0.089
0.034
0.135
0.024
0.092
0.077
0.076
0.036

127

Continued from previous page.
#

Final
HDR

sd

Total
mass (g)

sd

Root
mass (g)

sd

Total
mass (g)

sd

Root:
Shoot

sd

1

42.6

7.42

16.0

2.18

7.39

1.03

16.0

2.18

0.878

0.157

2

36.3

5.77

26.8

2.19

11.9

1.91

26.8

2.19

0.804

0.120

3

44.5

4.06

15.2

3.50

7.07

1.65

15.2

3.50

0.873

0.077

4

46.1

6.09

17.0

3.59

8.55

1.92

17.0

3.59

1.007

0.103

5

34.0

4.50

27.8

5.54

14.2

3.37

27.8

5.54

1.053

0.222

6

43.8

3.25

16.2

2.03

7.67

1.10

16.2

2.03

0.911

0.172

7

35.0

6.36

26.4

3.98

10.8

1.68

26.4

3.98

0.710

0.134

8

48.5

7.82

14.5

1.97

6.63

0.65

14.5

1.97

0.853

0.110

9

37.2

1.44

25.7

2.72

10.9

1.43

25.7

2.72

0.743

0.127

10

44.8

5.16

14.9

2.49

6.43

1.15

14.9

2.49

0.801

0.257

11

37.4

5.75

24.8

2.30

10.6

1.22

24.8

2.30

0.758

0.113

12

45.9

5.57

15.0

2.02

7.17

1.26

15.0

2.02

0.911

0.104

13

39.6

5.33

24.4

7.20

11.4

3.51

24.4

7.20

0.904

0.168

14

42.7

7.30

13.7

3.24

6.93

1.81

13.7

3.24

1.029

0.149

15

38.7

3.64

28.2

1.81

12.9

1.13

28.2

1.81

0.846

0.076

16

44.6

2.97

15.0

1.39

7.24

0.40

15.0

1.39

0.946

0.139

17

36.2

4.30

26.5

1.74

11.4

1.36

26.5

1.74

0.753

0.081

18

47.8

6.51

13.9

3.04

6.41

1.33

13.9

3.04

0.882

0.196

19

45.0

5.76

26.8

3.56

11.8

2.51

26.8

3.56

0.777

0.111

20

41.4

5.41

13.4

2.09

6.89

1.04

13.4

2.09

1.087

0.208

21

34.3

6.69

17.6

4.73

8.00

1.88

17.6

4.73

0.859

0.103

22

38.7

5.31

13.4

2.33

6.62

1.23

13.4

2.33

0.988

0.153

23

38.9

4.40

15.8

1.80

7.77

0.57

15.8

1.80

0.994

0.149

24

31.0

5.20

18.0

3.26

8.82

1.44

18.0

3.26

0.982

0.158

25

41.2

4.26

12.6

2.59

6.58

1.58

12.6

2.59

1.090

0.169

26

30.5

5.84

21.0

3.52

10.2

1.59

21.0

3.52

0.946

0.100

27

37.9

5.74

14.2

1.52

7.16

1.23

14.2

1.52

1.014

0.169

28

31.0

2.84

18.2

3.66

8.50

1.08

18.2

3.66

0.912

0.171

29

42.2

8.72

12.1

2.26

5.61

1.02

12.1

2.26

0.885

0.180

30

25.7

2.30

22.9

6.79

10.4

2.99

22.9

6.79

0.859

0.166

31

36.1

6.69

14.0

2.39

6.54

0.87

14.0

2.39

0.893

0.125

32

31.0

2.90

17.9

3.87

8.02

2.23

17.9

3.87

0.818

0.174

33

36.3

3.31

12.9

2.43

6.25

1.38

12.9

2.43

0.940

0.122

34

31.5

2.51

20.7

1.92

8.95

0.75

20.7

1.92

0.776

0.144

35

38.8

4.48

15.7

1.74

7.48

0.99

15.7

1.74

0.925

0.159

36

30.8

1.99

18.6

1.13

7.68

0.73

18.6

1.13

0.719

0.138

37

36.2

2.16

12.4

2.46

6.04

0.71

12.4

2.46

0.980

0.161

38

31.7

1.65

17.8

4.19

7.87

2.15

17.8

4.19

0.785

0.055

128

Appendix J: Field trial data

Table 1: The mean values and standard deviations (sd) for each response variables,
final height, total height growth, final root collar diameter (RCD), total RCD growth
and height to diameter ratio (HDR) for the Aleza Lake Research Forest field trial.

Species
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Pl
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx
Sx

Ash
Cont
Cont
Cont
CPLP
CPLP
CPLP
CPLP
CPLP
CPLP
CPLP
CPLP
UNBC
UNBC
UNBC
UNBC
UNBC
UNBC
UNBC
UNBC
Cont
Cont
Cont
CPLP
CPLP
CPLP
CPLP
CPLP
CPLP
CPLP
CPLP
UNBC
UNBC
UNBC
UNBC
UNBC
UNBC
UNBC
UNBC

Place
Cont
Cont
Tb
Bc
Bc
Bc
Bc
Tb
Tb
Tb
Tb
Bc
Bc
Bc
Bc
Tb
Tb
Tb
Tb
Cont
Cont
Tb
Bc
Bc
Bc
Bc
Tb
Tb
Tb
Tb
Bc
Bc
Bc
Bc
Tb
Tb
Tb
Tb

Rate
Cont
Cont
Cont
H
H
L
L
H
H
L
L
H
H
L
L
H
H
L
L
Cont
Cont
Cont
H
H
L
L
H
H
L
L
H
H
L
L
H
H
L
L

N
no N
yes N
no N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N
no N
yes N

Final
height
(cm)
45.4
40.6
37.4
24.2
44.1
41.0
46.2
44.9
40.9
42.7
38.1
44.2
40.4
45.3
47.7
48.4
35.2
38.7
44.0
47.3
43.3
47.5
44.4
47.5
45.7
49.6
48.1
48.5
46.2
45.1
52.6
45.5
48.9
46.7
50.6
49.5
49.7
47.6
sd
10.9
11.1
13.0
13.6
14.8
12.1
8.6
15.0
16.2
10.9
16.9
17.2
17.7
13.9
12.1
12.1
16.4
10.7
16.8
7.4
7.4
8.2
6.6
8.6
7.8
8.8
8.2
8.6
10.1
12.7
7.5
9.0
8.0
9.0
7.9
9.2
10.0
8.0

Total
growth
(cm)
35.2
31.2
28.0
12.1
34.7
30.5
36.1
35.6
30.3
32.3
28.5
35.2
29.5
35.9
36.8
38.3
25.0
29.5
33.6
21.5
22.2
25.1
21.7
23.7
23.6
27.6
24.7
25.0
22.5
22.5
28.4
23.5
26.5
24.5
27.6
26.2
26.0
23.4

sd2
10.5
11.5
12.7
15.0
15.2
12.8
8.1
15.7
16.6
11.1
18.1
17.6
17.2
13.0
12.2
12.1
17.2
11.8
17.7
6.5
5.6
8.6
5.2
7.0
5.9
8.4
6.7
8.3
6.8
10.3
7.7
7.4
7.4
7.3
6.3
7.7
7.8
6.9

Final
RCD
(mm)
9.60
9.25
8.25
6.86
9.27
8.75
9.64
9.27
8.41
9.45
8.56
9.18
8.93
9.02
9.17
9.55
8.45
8.37
9.78
8.65
9.23
8.81
9.48
9.10
7.98
9.15
8.38
9.73
9.31
10.42
9.35
10.14
9.11
9.04
9.21
8.91
9.58
9.98

sd3
2.63
1.94
1.99
2.23
2.38
1.84
2.01
2.32
1.88
1.76
1.78
2.13
2.78
1.44
1.55
1.53
1.95
1.73
2.71
1.23
1.87
1.19
1.48
1.37
1.21
1.41
1.16
1.62
1.79
2.37
1.24
2.26
1.10
0.88
1.28
1.72
1.51
1.38

RCD
growth
(mm)
5.74
5.80
4.94
3.24
5.70
5.11
6.13
5.75
4.91
5.62
5.01
5.46
5.34
5.49
5.58
5.88
4.71
4.77
6.09
3.94
4.09
4.09
4.91
4.18
3.30
4.41
4.01
4.87
4.78
5.85
4.71
5.47
4.75
4.71
4.53
4.59
4.72
5.54

sd4
2.55
2.14
1.84
2.06
2.50
1.79
1.86
2.09
1.96
1.95
1.65
2.26
2.90
1.31
1.61
1.64
1.92
1.90
2.48
1.10
1.64
1.39
1.35
1.26
1.22
1.47
1.04
1.42
1.47
2.30
1.37
2.05
1.10
0.83
1.24
1.43
1.44
1.16

HDR
4.88
4.44
4.50
3.50
4.71
4.64
4.91
4.76
4.75
4.57
4.38
4.67
4.44
5.02
5.24
5.06
4.03
4.64
4.46
5.48
4.80
5.41
4.75
5.24
5.76
5.52
5.76
5.07
5.06
4.39
5.65
4.58
5.42
5.19
5.53
5.61
5.23
4.81

sd5
1.01
1.04
1.29
1.46
0.89
0.94
0.97
1.00
1.33
1.08
1.71
1.12
1.19
1.26
1.22
0.94
1.31
0.94
1.13
0.48
0.97
0.79
0.73
0.70
0.77
1.22
0.72
1.06
1.11
1.11
0.69
0.81
0.97
0.96
0.77
0.81
0.99
0.80

129