PESEAPCH NOTES BRITISH No. 42 CDLUMBIR FDRE5T SERVICE VICTORIA, B.C., CANADA THE DURABILITY OF SCARIFIED SEEDBEDS FOR SPRUCE REGENERATION By J . W. C. ARLIDGE Research FOREST Division SERVICE D EPA RTM EN T OF LANDS, FORESTS, AND WATER RESOURCES 1967 T H E D U R A B I L I T Y OF S C A R I F I E D SEEDBEDS FOR S P R U C E R E G E N E R A T IO N By J, W. C. A r l i d g e B. C. F orest S ervice Research Notes are issued a t ir r e g u la r in te r v a ls and d is trib u te d on the b asis o f t h e ir ^ i v i d u a l in t e r e s t . T h erefore, i t may not be p ossib le fo r persons o r organ isation s to maintain complete f i l e s inasmuch as c e rta in numbers may p erta in o n ly to F orest S ervice problems and hence be issued o n ly to S ervice personnel. S ca ri fie d seedbeds in O ( D e v i l 's Club) site type are rapidly invaded by t h i m b le b e r r y (Rubus parvuflorus) . Assistant is standing at centre of scar ifi ed seedbed that was bare mineral soil 4. 9 feet wide three years be fore. Vegetation on areas not sc ar ifi ed was one to two feet high at that time. - Ill SUMMARY The effective life of mac hi ne -sc ari fi ed seedbeds was investigated on 17 areas in the P r in c e Geo rg e F o r e s t District. A l l areas w er e on sites of average or better productivity f o r the region. On each area f r o m one up to a maximum of five sample plots were established, making a total of 33 plots distributed o ver a number of sites, ye ar s, and methods of scarification. In each plot, seedbeds were selected at random along s ca r ifi ed strips so that they represented a range in size f r o m one foot square to 6.6 feet square. Seedbeds w er e seeded in the year of scarification (SYO), and one (SYl), two (SY2), three (SY3), and four (SY4) years after being scarified. When all these seeding treatments had been concluded, 310 seedbeds were under observation on each plot. Because nature could not be relied upon to provide a constant supply of seed, seedbeds were spot-sown a r t i fi c i a ll y to simulate an annual natural seedfall. Thus the results of the study are also an indication of what to expect after a rt if ic ia ll y seeding strips which w ere scarified o ri gi n a lly to induce natural regeneration. The crite rio n of effectiveness was te rm ed "s u c c e s s " and it was rated as the per cent of seeded seedbeds with one or more healthy spruce seedlings in relation to the age and size of the seedbed since the date of scarification. In addition to these main related facto rs, the influence of site-quality, size of tra ct o r, and the interval of time between logging and scarifying also was examined. Seeding ye ar had a definite effect, and success decreased with the passage of time between scarifying and seeding. Mean success was 62.8 per cent fo r SYO, and 52.7, 38.7, 36.9, and 29. 0 percent re sp ec t iv e ly for S Y l , SY2, SY3, and SY4. Success varied d ir ec t ly with seedbed si z e . On large seedbeds, survival was g r e a t e r and the decre ase due to see ding-year effect was much less than on small seedbeds. The o v er a ll success was 44.0 per cent at the end of the fi r s t growing season, and 45.7, 40.1, 33.9, and 26.9 per cent re sp ec t iv e ly at the end of the second, third, fourth, and fifth growing seasons (when seeding year was ignored and the per cent of all seedbeds with one or more spruce seedlings was averaged each season). Th er e were no such cle ar r e s ults fo r success in relation to the size of the bulldozer, s i t e - t y p e , and interval of time between logging and s c a r i f y i n g . because only a few confounded conditions were available for sampling. Ho wever, there are indications that: ^ - success on plots s ca r ifi ed by large tractors is g r ea t er than on plots s ca r ifi ed by medium and small t ra ct o rs, - plots on the vegetation site-type classif ied as A ra li a - O a k fe r n had slightly better success than plots on a D e v i l ' s Club site, and - differences between pre -lo gg in g and post-logging scarification w er e not significant. A O When the ' per cent success' of spruce is converted to a more f a m ili a r stocking per cent fo r the average sc ar ifi ed acre on a m i l - a c r e basis, the principal results are: - a stocking of 50. 5 per cent in four years if the area was naturally or a r t if ic ia l ly seeded the same y e ^ it was scarified, - a decrease to 32.8 per cent stocking if seeding occurs one year after site preparation, and - unsatisfactory stocking if seeding occurs at intervals longer than one year after scarification. In this instance, it has been predicted that, to ensure success, the number of viable seeds required would range fr o m as many as 11 fo r a 6. 6-foot-square plot to 25 fo r a one-foot-square plot. Other species were present on the seedbeds together with the spruce. They were balsam, Do ugla s-fir, lodgepole pine, hemlock, aspen, cottonwood, and birch, all fr o m natural seedfall. Only balsam and birch were found on all p lo t s. The success of balsam and birch, rated in the same way as spruce, v ari ed with seedbed size but not with seeding year. Turning now to measures of growth, the average height of tallest seedlings at the end of four growing seasons was: - spruce - 3 . 9 ins. , - balsam - 1 . 9 ins. , and - birch 11.9 ins. The average height of spruce seedlings did not vary with seedbed size but after the second growing season the seeding -ye ar effect resulted in decrea sed average height of spruce and balsam seedlings, i . e . the average height of S Y l seedlings was less than SYO seedlings of the same age, that of SY2 seedlings less than S Y l seedlings, and so on. The vigorous growth and the abundance of birch seedlings are a potential threat to spruce seedling survival. The v e r y slow height growth of the spruce seedlings is a disturbing feature, esp eci al ly when we re ca ll that the sample areas have high sitevalues. If a ge ner al ly poor seedling performance is confirmed by a survey of all sc ar ifi ed areas , then site preparation and planting, rather than scarifying and seeding, is recommended on D e v i l ' s Club and A r a l i a Oakfern sites to ensure a more profitable realization of their potential productivity. 0 T A B L E OF CO NT ENT S T I T L E PAGE P H O T O G R A P H - Invasion of sc ar ifi ed seedbed by thimbleb er ry - _____________ ii S U M M A R Y __________________________________________________________________________ iii I N T R O D U C T I O N __________________________ 1 O B J E C T I V E ______________________ 2 METHODS AND PR O CE D URE S __________________________________________________ 2 A N A L Y S E S OF D A T A _____________ 5 RES U LT S AND DISCUSSION______________________________________ 5 Effects of T i m e and Seedbed Site________________________ 6 Other E f f e c t s .............. 9 _ Other S p e c i e s ..................... Height of Seedlings ____ _ _ 10 _ _ 12 I N T E R P R E T A T I O N OF RE SU LTS IN TERMS OF S P O T SEEDING_____________ 15 O BSERV A T IONS....................... ..... . ...... ... .... ............ ..... ............................ .. ....... 16 CONCLUSIONS AND R E C O M M E N D A T I O N S ______________ _ 18 _ R E F E R E N C E S ............... 20 APPENDIX Tabulated Summaries of Data FIGURES F ig . 1. Location of sample plots _____ 2. P e r cent of seeded seedbeds with spruce seedlings (adjusted to base year 1959)___________ ______ 3 Page 3. P e r cent of seeded seedbeds with spruce seedlings (not adjusted to 4. base year) ___________________ P e r cent of seeded seedbeds with spruce, balsam, and birch se e d li n g s ______________________ 5. 11 A v e r a g e d height of tallest spruce, balsam, and birch se e d li n g s _______________________________ 6. 8 13 A v e r a g e d height of tallest spruce, balsam, and birch seedlings on AD and O site types _________ 14 INT ROD UCT IO N In the spruce-alpine f i r forests of interior British Columbia scarification with a bulldozer blade is proving to be an expeditious means of site preparation, preceding natural or artifi cia l regeneration. The annual scarification pr ogr am to promote natural seeding has increased f r o m trials on 243 acres in 1956 to 15, 530 acres during 1965, even though the treatment is ge ner al ly re str ict ed to about 30 per cent of the logged acreage. In the P r i n c e Geo rg e F o r e s t District, the results of a natural regeneration survey, based on 6,549 acres of scarification, have been promising and indicate that white spruce should be w e ll -r e p r e s e n t e d in the new stand. In fact, Gilmour and Konishi (1965) report that the average spruce stocking is 44 per cent by m i l - a c r e quadrats, and that, if all species are counted, the stocking is 49 per cent with a range f r o m 4 to 94 per cent. This variation in natural stocking is not surprising. It stems fr o m the fact that many events control the success or failure of this method of regeneration and seldom occur in an ideal sequence of desirable interactions. Although we need not list all the events, the p r i m a r y factors dictating success or failure are abundance of seed supply, control of biotic enemies, exposure of mineral soil in adequate numbers of well-distributed seedbeds, absence of brush and weeds, favourable weather, and (when 10 or more dollars are invested per acre in scarification) the durability of the prepared seedbed. It is of value to know the effective life of a seedbed because, if it spans sev er a l ye ars, it provides a welcome leeway in the vital matter of timing operational scarification p ro gr a ms . F i r s t , the timing of scarification to coincide with v e r y good seed crops is less cr itical. Secondly, it becomes more practical to cope with administrative difficulties (p. 15 Gilmour and Konishi 1965). Thirdly, it affords an opportunity to seed a r t if ic ia l ly in a ye ar subsequent to the year of scarification providing the prospect of successful natural seeding dims in the face of lost seed sources or poor seed-crops. Obviously, s e v er a l questions a ri se . Is the life-span one, two, or five years after the year of scarification? How important is size of the seedbed, with particular refe re nce to its re-occupation by weeds (Stettler 1958)? Some of the answers have resulted fr o m the present study.* Its main purpose is to advise on the length of time sca rifie d seedbeds remain effective media fo r establishment of spruce regeneration. It reports also on behaviour of the associated species of balsam and birch, and comments b r i e fl y on the influence of vegetation site-type, tracto r siz e, and interrelation of times of logging and scarifying with the speed of vegetative invasion of prepared seedbeds. '■'Based upon results fr o m Experimental P r o j e c t 528 - The Influence of Ti m e on the Effectiveness of Scarified Seedbeds. - 2 - OBJECTIVE The objective was to determine how long s ca r ifi ed seedbeds remain effective as media f o r the germination, survival, and growth of spruce. METHODS AND PROCEDURES This study was c a r r i e d out in the P r i n c e Geo rg e region on a number of timber sales s ca r ifi ed by normal operational procedures. Scarifying equipment included a va ri e ty of c r a w l e r tractors equipped with bulldozer blades. Within selected timb er sales, plots w er e established after examination showed they were la rg e enough, sufficiently uniform with rega rd to site, and had the required range in size of seedbeds. Fi gu re 1 and Table 1 show the number and distribution of the plots finally selected. Each plot consists of 310 mineral soil seedbeds produced by scarification. The individual seedbeds w er e selected and staked on ir r e g u la r transects tra ver sin g the plot area. The minimum dimension of m a r g i n -t o - m a r g in width of mineral soil was measured on each seedbed. The margin of a seedbed was either fore st fl o or or slash accumulations. The minimum width recorded was one foot, and the la rg es t 6.6 feet. L a r g e s ca r ifi ed areas frequently had s e v er a l maximum­ sized seedbeds on them with their centres seven or more feet apart. Within each plot, 50 seedbeds, selected at random, were seeded the same ye ar they were sc ar ifi ed (seeded year ze ro or SYO). Each succeeding year 50 seedbeds w er e seeded ( S Y l , SY2, SY3, SY4), and an additional 15 seedbeds w er e hand-scarified and seeded each year to approximate the original conditions of scarification. Seeding was done each fall starting late in September and was completed by October 15. B e fo r e seeding, all natural coniferous seedlings w er e re mo ved fr o m the seedbed. Renewed seedbeds were checked for width, cl ear ed of vegetation with a sharpened dutch hoe, and then seeded. Seed was sown near the stake, at the centre of the seedbed. The seeder was held about 10 inches above the ground and the seed fe l l within a cir cu lar area averaging 10 inches in diameter. A Swedish hand seeder (page 42, Res earch Re vi ew , 1958), set to d el iv er approximately 12 viable seeds, was used the fi r s t two years (1958 and 1959). F o r the remaining years (I960, 1961 and 1962), the " M and B" seeder was used (page 34, Research R ev ie w , I960). It d el iv er ed approximately 15 viable seeds. Fi gu re 1 Number and approximate location of sample plots. Inset outline of British Columbia shows general location of study area. Table 1. Distribution of Plots Number T ractor of Plots Size F orest Site (1) Type Year Scarified Scarified O 1957 +2 Large 1 N a v o r P . W . C . , M a ry Lake O 1957 +1 Medium 2 A l e z a Lake, F o r e s t , R e s . o 1957 +1 Small 4 11 It 11 o 1957 -0 Medium 3 11 11 11 o 1957 -0 Small 5 Tl ft 11 o 1957 -0 Large 1 o 1957 +0 Large 1 o 1958 Not Log ge d Medium 2 A l e z a Lake, F o r e s t Res. o 1959 +5 L a rg e 1 Crooked R i v e r P . W . C . AD 1958 Not Log ge d Medium 1 A l e z a Lake, F o r e s t Res. AD 1958 -0 Medium 4 Crooked R i v e r P . W. C. AD 1959 +5 L a rg e 2 AD 1959 +1 L a rg e 2 AD 1959 +1 Medium 1 " " AD 1959 Not Logged Medium 1 n n AD I960 +0 L a rg e 1 15 Mile Rd. , Wells Rd. AD 1961 +1 L a rg e 1 Crooked R i v e r P . W . C . Location Sinclair Mills 11 II II It t* N a v o r P . W . C . , M a r y Lake (1) o = Oplopanax Site Type. (2) Years scar ifi ed before (-) logging or after {+) logging. Stone Creek rt AD := A ra lia - ■Dryopteris Site Type. ri The seeded seedbeds w er e examined in e a r ly summer (June to mid-July) and the fall (September) of 1959 and I960. In 1961, 1962, and 1963 they were examined only in the fall. Spruce and other t ree seedlings wer e counted and recorded. On the second fall examination and on each succeeding examination, the height of the tallest seedling of each tree species present was recorded. Seedbed examinations made during the five years of the study totalled 17, 980. Control data allowed adjustment fo r variations in weather conditions, natural seedfall, rodent depredations, and other uncontrolled varia ble s. It was assumed that the results f r o m SYO seedbeds and the se ri es of renewed seedbeds, seeded in each of the succeeding four ye ars, va rie d in response to the uncontrolled variables only, whereas all the other seeded seedbeds had the added effects of passage of time. Complete control was not attained because renewing seedbeds by hand methods did not make them identical to the newly sc ar ifi ed condition. The control data f r o m the SYO and the renewed seedbeds permitted the adjustment of all data to a base ye ar, thus reducing the effects of uncontrolled var iables. The year 1959 was selected as base year because monthly precipitation and mean monthly temperatures during the growing season were close to the lo n g -t e rm averages as measured by weather data f r o m the Pr in c e George A i r p o r t weather station. A N A L Y S E S OF D A T A Reg re s si on analyses of the number of seedlings on siz e of seedbed wer e made and the effects of time of seeding and seedbed size were c le a r ly indicated. Analyses w ere then made on the basis of number of seeded seedbeds with one or mor e seedlings at the end of each of fiv e growing seasons. Comparisons between t r a c t o r - s i z e s , sit e-types, and t i m e - o f scarification to t i m e -o f- l o g g in g w er e difficult because sampling was not orthogonal. RES ULTS AND DISCUSSION Results are reported in terms of per cent of seeded seedbeds with one or more seedlings and this is te rm ed ' success' . Tabulated summaries of the data are presented in the appendix. Effects of T im e and Seedbed Size The decreasing effectiveness of the seedbeds with passage of time after scarification, due mainly to regrowth of vegetation, is apparent in the success by seeding ye ar s. Mean success of the seedbeds seeded the same year as sc a r ifi ed (SYO) is 62.8 per cent; and 52.7, 38.7, 36. 9, and 29. 0 per cent r e sp ec t i ve ly fo r S Y l , SY2, SY3, and SY4. Size of seedbed had an important effect on success. Success was l ow er on small seedbeds than on l a r g e r ones, and the decrease with successive years and with time of seeding was also g r ea t er on small seedbeds than on large ones. Fig ure 2 shows the effects of seedbed size and the adverse effects on the establishment of seedlings with the passage of time between scarification and seeding. O v e r a ll success in terms of per cent of seeded seedbeds with one or more seedlings was 44.0 per cent at the end of the fi r s t growing season, and 45.7, 40.1, 33. 9 and 26. 9 per cent re sp ec t iv e ly at the end of the second, third, fourth, and fifth growing season. The seeding year with the best results is SYO. The y e a r ly decline in success of these seedbeds seeded during the scarification year is c l e a r l y shown fo r a period of four ye ar s. At the end of four growing seasons, 23.3 per cent of the smallest s i z e - c l a s s seedbeds have one or more seedlings, while 51.7 per cent of the larg est s i z e class have one or more seedlings. Th ere is no sign of a levelling off of the annual decrease in number of seedbeds with seedlings. The steady decrease in success f r o m year to ye ar with no sign of levelling off may be cause f o r concern. Ho wev er, the above results are derived f r o m data adjusted to minimize the effects of the uncontrolled variables (weather, natural seedfall, rodent depredations) and it is assumed that these results depict the situation that would pr ev a il under a continuous regime of the base ye ar, 1959. But weather, natural seedfall, and other conditions varie d f r o m year to y e ar . The data without adjustment, presented in Fi gu re 3, shows an increase in average success with the passage of time, due to the seeding in of natural seedlings, 46.0 per cent at the end of the fi r s t growing season, and 54.5, 55.1, 57.4 and 62. 0 per cent res pe ct iv e ly at the end of the second, third, fourth, and fifth growing season. Ho we ver , the decrease in germination and survival with the passage of time between scarification and seeding (seeding year effect) and the effect of seedbed size are as prominent as in the adjusted data, a further indication of the lasting effectiveness of the l a r g e r seedbeds. Seedbed ’. • 7 Size-C lass I 3-2 1st. G r o w i n g 4*7 6-2 Season .SYO 60 40 SY 1 SY2 SY 3 s y 4 20 0 2nd. Growin ) Season 80 60 i/> O z 40 mu 20 in O z 60 o UJ LU LO 40 20 CO o J. UJ CO o to o 80 tZ LU 60 U 0£ LU 40 O. Fig ure 4 P e r cent of seedbeds seeded with spruce, balsam, and birch seedlings at the end of the second, third, and fourth growing seasons, by seeding ye ars . - 12 - Height of Seedlings At the end of the second growing season and each examination thereafter the tallest seedling of each t ree species found on a seedbed was measured. Fi g u re 5 is a bar graph of the averaged heights arranged by seeding ye ars. A v e r a g e height of tallest seedlings decreases with seeding year at the end of the third and fourth growing season fo r spruce and balsam. The ir r e g u la r it y of seeding ye ar effect on spruce and balsam at the end of the second growing season is thought to be the result of differences in growth in various ye ar s, due principally to weather. By the end of the third growing season these differences are less and do not mask the seeding year effect. The r e v e r s a l of seeding year effect shown by birch heights is the result of seedling age not being related to seeding ye ar. Most birch SY3 seedlings are not 2 years old, but 4 or 5 years old. It is important to notice that growth (difference between averaged height at the end of the third and second growing season, and at the end of the fourth and third growing season) decreases with seeding ye ar fo r all s p e c i e s . Spruce height was not found to be related to seedbed si z e, and it is assumed that the same condition holds true f o r balsam and birch height growth. Neither was there any indication that tra ctor siz e, nor t i m e - o f - s c a r i f y i n g to t i m e - o f- l o g g in g had an effect on height growth. Th er e is evidence that averaged heights of spruce and birch, but not balsam, are g r ea t er in AD site type than in O site type. Fi g u re 6 shows the averaged heights fo r plots in AD and O site types arranged by seeding ye ar s. These results are no doubt responsible in part fo r the impression that AD site types were more successful than O site types. Spruce grew better than balsam, and balsam is perhaps not a serious competitor with spruce. On the other hand, the vigorous growth and abundance of birch seedlings are a threat to the survival and development of spruce seedlings. The poor height growth of spruce and balsam seedlings is noteworthy. I/I 4) u c I o Av er ag ed height (in inches) of tallest spruce, balsam, and birch seedlings at the end of the second, third, and fourth growing seasons, by seeding ye ars . A ve r a g ed height (in inches) of tallest spruce, balsam, and birch seedlings at the end of the second, third, and fourth growing seasons on AD and O site types, by seeding years I N T E R P R E T A T I O N OF RES ULTS IN TERMS O F S P O T SEEDING On the basis of this study and s ev er a l assumptions, the results fr o m spot seeding s ca r ifi ed areas when natural seed is unavailable or inadequate can be predicted. Scarification as practiced in the P r i n c e Georg e region results in mineral soil exposure that averages 34 per cent of the area, or 15, 000 sq. ft. per acre (Gilmour and Konishi, 1965, page 7). Assuming that seedbed sizes occur in the same ratio as found fo r the plots of this study there is room fo r 660 seedbeds per ac re distributed as follows: Seedbed S i z e - C l a s s - ( fe e t ) Number of seedbeds 1. 0-2.4 2.5-3.9 4.0-5.4 5 .5 - 6 .6 145 136 97 282 This corresponds to the aver age distribution of seedbeds found by Gilmour and Konishi - that is, 65 per cent (= 650) of the m i l - a c r e s on an ac re have one square foot or more of seedbed. Assuming that the 660 available seedbeds are spot-seeded and applying the results f r o m summary 2 in the appendix, the number of stocked seedbeds was calculated and converted to a stocking figure for SYO and S Y l seedbeds at the end of the fourth growing season and f o r SY2 seedbeds at the end of the third growing season. These results are presented in Table 2 on page 16. Included is the number of viable seeds required to produce two surviving seedlings at the end of the fourth growing season, estimated f r o m data not used in this report. It is evident f r o m these results that seeding the same year as scarification is essential to obtain the best results. The predicted number of stocked seedbeds at the end of the fourth growing season following seeding produces adequate stocking of 50. 5 per cent on a m i l - a c r e basis and the quantity of seed required is small. Seeding one growing season after scarification reduces stocking to 32.8 per cent, and doubles the amount of viable seed required. When seeding is delayed until two growing seasons have passed after scarification, stocking is unsatisfactory and the quantity of viable seed required is la rg e. It should be noticed that the SY2 stocking of 28.7 per cent is at the end of the third growing season after seeding. Advance regeneration, regeneration of other coniferous species, and regeneration occurring on seedbeds other than mineral soil would improve stocking slightly. € Table 2. P e r cent Stocking on A v e r a g e Sc arifie d A c r e Success ^■ Seedbed Si z e -C l a s s Seedbeds feet Available SYO SYl SY2 1. 0-2.4 145 61.8 25. 9 21.6 89 38 31 8 16 25 2.5-3.9 136 64. 3 37. 9 31. 0 87 52 42 5 13 13 4. 0-5.4 97 72.7 55. 1 46. 0 71 53 45 3 11 13 5 .5 - 6. 6 282 91.6 65.6 59. 8 258 185 169 2 9 11 Total 660 505 328 287 50. 5 32. 8 28.7 M i la c r e ]Per Cent Stocking No. of Stocked Seedbeds SYO S Y l SY2 No. of Viable Seeds per Seedbed SYO S Y l SY2 , 1. Success - per cent of seeded seedbeds with one or more seedlings and is rated at the end of the fourth growing season fo r SYO and S Y l and the end of the third growing season fo r SY2. Scarification can be made more effective by increasing the area of exposed mineral soil. This would not only provide mo re seedbeds, but would also increase the proportion of the la rg e seedbeds that are more eff ect ive . Cost of scarifying could be expected to increase by this practice. OBSERVATIONS A study such as this with repeated examinations of the same areas engenders in the examiner a f a m i li a r it y with the plots and their responses. The following observations are based on f a m il ia r it y and not experimental evidence but 1 hope they add to this study. Plots on sandy loam soils had more seedlings in SYO and S Y l years than plots on silty and clay soils. Ho we ver , sandy loam plots were quickly ov ergrown with vegetation. Es pe cia lly is this the case in Oplopanax ( D e v i l ' s Club) site type where sandy loam plots were obliterated in three years with a rank growth of thim ble be rry (Rubus pa rv ifl or u s) three feet tall. (See photograph page ii) Seedbeds with a rough surface had more seedlings than smooth seedbeds. Even the slight roughening made by tra ctor tracks improved the seedling catch. On the other hand, so -c a l le d mixed seedbeds, that is, a mixture of duff and mineral soil rol led up by the bulldozer blade and then spread out, were poor seedbeds in terms of establishment of seedlings; but height growth of the few seedlings established on mixed seedbeds appeared better than av er ag e. To produce the ideal seedbed requires an implement that s c r e e f s , that is, scrapes off the vegetation and most of its roots, and that cultivates or harrows the bare mineral soil to produce a rough seedbed. F r o s t heaving oc curred on seedbeds on heavy-textured soils, but is not considered a serious factor in spruce establishment. A re c o r d of fr ost heaving was kept fo r s e v e r a l plots e a rl y in the study. F r o s t heaving of spruce seedlings was recor ded on 267 seedbeds. Two growing seasons later 243 of these seedbeds still had spruce seedlings on them. Many of the seedlings had exposed '‘ hockey stick" roots, but otherwise did not appear to diff er in vig or or average height f r o m normal s ee dl in g s. T h im b le b e rr y is the most vigorous plant invader of sc ar ifi ed seedbeds in the study area. It grows f r o m root sprouts, pr oliferates rapidly f r o m its rhizomes and can obliterate a large seedbed in three ye ar s. It competes with spruce seedlings fo r moisture and nutrients and produces a dense shade. Most spruce seedlings that survive its competition are smothered by its heavy leaf fall. T h i m b l e b e r r y is most plentiful in the O site type, esp ecially after logging. Birch seedlings are vigorous competitors, too. The abundance of birch seedlings varies with number of seed tr e e s , and one birch seed t ree per acre can establish seedlings on a large number of sc a r if ie d seedbeds. The felling of birch residuals would gr eat ly reduce the number of birch seedlings, although there would still be a seed source in the unlogged margins. A ft e r the third year many birch seedlings are browsed sufficiently to check their growth, but not, unfortunately, to reduce the threat to survival of spruce se e d ­ lings. Western coolwort (T i a r e l l a unifoliata) is the herbaceous plant most frequently found on s ca r ifi ed seedbeds in O and AD site types. It begins to occupy seedbeds after two or three ye ars . It is, of course, a competitor, but more in the sense that it occupies space and is thus more serious on small seedbeds than large ones. Oak fern (Gymnocarpium d r y o p t e r i s ), sars apa ri ll a (A ral ia nudicaulis), woods' horsetail (Equisetum sy lvaticum) and bunchberry (Cornus canadensis) are also, more or less , the same kind of competitors, become established on seedbeds after two or three ye ar s, but occur less frequently than Tiarella. Occasionally small areas oc curred in slightly concave positions that re c e iv e d surface drainage f r o m the surrounding te rrain. These places usually had low success. The seedbeds tended to be definite depressions that flooded f r o m spring snow melt, and in the fall in years when there w er e heavy rains. The few successful seedbeds in these places w er e mounds or hummocks. Vegetation of fer ed serious competition on the mounds. Sedges (Ca re x spp.), Indian reed grass (Cinna l a t ifo lia ), bluejoint grass (Calamagrostis canadensis) and horsetails (Equisetum spp.) not only became active competitors within two or three growing seasons, but their lit ter smothered seedlings. Unfortunately no plots in Cornus-Moss site type w er e found fo r this study. The Cornus-Moss site type is well-suited fo r scarification. It has a livin g-m os s and raw-humus l a ye r s e v e r a l inches thick, l e s s e r vegetation is re la ti ve ly poor in species and abundance, approximately 7 0 per cent of the plant roots are in the humus and top inch or two of the soil. F u r th e r m o re , observations show that in the C - M site type scarified (screefed) seedbeds remain f r e e fr o m vegetation fo r four to five ye ars . Glew (1963) found scarification costs to be low on C - M site types. CONCLUSIONS AND REC OM ME N D A TI ON S F o r best results sc a r if ie d areas should be seeded naturally or a r t i fi c ia l ly the same year, and not later than one growing season after scarification. At present, prediction of good seed crops is uncertain, and it is impractical to schedule scarification to years of good seed crops fo r it means a crash p r o g ra m to s c a r i fy the backlog of unregenerated areas built up between good seed ye ar s. A r t i f i c i a l seeding is an a l ­ ternative when seed crops fa il, but this also presents difficulties. Broadcast seeding requires larg e quantities of seed which is expensive and often is not available at any pri ce. Spot-seeding gr eatly reduces the quantity of seed required, although labour costs are increased. Improved scarification to increase exposure of mineral soil is recommended. The maximum area possible is limited to 60 to 70 per cent of the total area because of the space occupied by stumps and slash accumulations, and an ir r e g u l a r distribution of regeneration is unavoidable. The lack of a difference in results f r o m p re -l og gin g and post­ logging scarification suggests that both leave and cut strips on alternate cl ear-cut strip timber sales be sca rified . The leave strips should be w int er -l ogg ed as soon as regeneration is established. The height of spruce seedlings in this investigation averaged only 3.9 inches at the end of four growing seasons. This height growth (the average of the tallest seedlings on each seedbed) seems poor f o r sites of as high potential growth as the AD and O site types. R e ­ surveying is recommended f o r some of the sc ar ifi ed areas on which regeneration surveys have been made. The main purpose would be to assess the growth of the regeneration and incidentally any change in stocking. If the re su rv ey confirms the poor growth shown in this investigation, then a strong case has been made fo r planting these sites rather than scarifying them. To re a li z e the high potential productivity inherent in O and AD site types, quick and adequate restocking with welldistributed thrifty spruce seedlings is essential. Investigation of mechanical methods of site preparation for planting is warranted. Site preparation fo r planting can increase survival and growth of planted stock by reducing competition fr o m vegetation, reduce planting costs, and improve spacing and stocking. With adequate site preparation the possibility of bullet or tube planting should not be overlooked. On the basis of the results of this study and experience, I suggest that cut-over areas in O site type be regenerated by planting, accompanied by site preparation, in o rd er to re ali ze the high growth potential of these sites. Scarification is suggested fo r AD site types provided further study shows growth of regeneration to be satisfactory. Although there were no plots in CM site types in this study, I believe that regeneration can be satis fact or ily established on this site type by scarification. « * 5|« REFERENCES Decie, T . P , , and F r a s e r , A. R. , 1961. Miscellaneous notes on scarification tri a ls, P r i n c e Geo rg e F o r e s t District, 1956-59. B. C. F o r e s t S e r v i c e , Res ear ch Note No. 36. Gilmour, J. R. and Konishi, J . , 1965. Scarification in spruce-alpine f i r type of the P r i n c e Geo rg e F o r e s t District. B. C. F o r e s t S e r v ic e , F o r e s t Management Note No. 4, Glew, D. R. , 1963 . The results of stand treatment in white spruce-alpine f i r type of the northern interior of British Columbia. B. C. F o r e s t S e r v i c e , F o r e s t Management Note No. 1. Illingworth, K . and A r l i d g e , J. W. C. , I960. Interim report on some fo re s t site types in lodgepole pine and spruce-alpine f i r stands. B. C. F o r e s t S e r v i c e , R es ea rc h Note No. 35. Rieche, K. W . , 1961. A pr el i m in a ry study of the economic use of c r a w l e r tra ct or equipment fo r scarification. B. C. F o r e s t S e r v ic e , Engineering Se rvi ce s Division. Unpublished Report. Stettler, R. F . , 1958. Development of residual stand of interior spruce-alpine f i r during the fi r s t 28 years following cutting. B. C. F o r e s t S e rv ic e , R es ea rch Note No. 34. A P P E N D I X Tabulated Summaries of Data Summary No. 1. P e r cent of seeded seedbeds with spruce seedlings (adjusted to base ye ar, 1959) Seedbed S i z e - c l a s s (feet) At the end of Seeded Year F i r s t growing season SYO SYl SY2 SY3 SY4 1. 0 - 2 . 4 2 .5 - 3 .4 4. 0-5.4 5 .5 - 6 .6 Mean 67.4 37. 0 31.4 21 . 2 58.7 33.7 30.4 20.7 19.6 75.9 45. 2 48. 5 29.2 79. 1 57.4 58.7 58. 0 47. 8 75. 3 46. 1 45. 2 37. 5 29. 0 20. 1 21.8 Mean Second growing season 44. 0 SYO SYl SY2 SY3 49. 5 32. 3 18. 5 20. 3 51. 3 39. 8 31.6 31. 8 72.2 49. 2 48. 2 40. 2 72. 2 63.6 53. 0 51. 6 Mean Third Growing season 45.7 SYO SYl SY2 34. 9 20. 1 10. 5 46.6 32. 8 18. 5 69.2 50. 5 37. 7 68. 0 55.6 41. 3 Mean Fourth growing season c 62. 1 42. 0 26.4 40. 1 SYO SYl 23.3 11.2 24.6 20. 8 46. 5 42. 5 51.7 41.7 Mean Fifth growing season 67. 5 49.6 40. 0 36. 1 45. 1 27. 9 33. 9 SYO 11.7 18. 8 26. 0 39. 8 26. 9 Summary No. 2. P e r cent of seeded seedbeds with spruce s eedlings (not adjusted to base year) • Seedbed S iz e - Class (feet) Seeded Year At the end of F i r s t growing season SYO SYl SY2 SY3 SY4 1 .0 - 2 .4 1 2. 5-3.9 4. 0-5.4 70.4 37. 9 33.0 19. 8 12. 5 67. 2 36.7 38. 9 28. 9 20. 5 79.7 46.4 53. 0 44. 3 20. 3 5 .5 -6 .6 90.4 59.7 61.4 53. 5 39.6 SYO SYl SY2 SY3 59.4 38.6 22.4 19.3 70. 9 52. 3 38. 0 32.4 80. 3 54.4 50.7 44.4 90. 1 73. 1 66. 7 60.7 Mean Th ir d growing season 84. 3 48. 1 49. 1 39.4 24. 3 46. 0 Mean Second growing season Mean 83. 5 59. 8 48. 2 39.4 54. 5 SYO SYl SY2 59. 0 32. 3 21.6 66. 0 45. 1 31.0 68.4 54.7 46. 0 89.0 77. 0 59. 8 Mean 80. 8 57. 1 39.6 55. 1 Fourth grow ing season SYO SYl 61.8 25. 9 64. 3 37. 9 72.7 55. 1 91.6 65. 6 57.4 Mean Fifth growing season 83. 1 45. 8 SYO 41.7 75. 0 50. 0 75. 0 62. 0 • Summary No. 3. P e r Cent of seedbeds with spruce, balsam and birch see dl in g s. Spruce Balsam 83. 5 59. 8 48. 2 39.4 20.4 11.4 26.7 35. 2 54.7 43. 2 50. 1 35. 2 54. 5 22.6 44. 9 80. 8 57. 1 39.6 35. 2 26. 9 35. 1 41.4 55. 2 48. 3 55. 1 31. 3 50. 3 83. 1 45. 8 55. 1 34.7 50. 2 47.6 57.4 41.3 48.4 Birch Seeded Year At the end of Second growing season SYO SYl SY2 SY3 Mean Third growing season SYO SYl SY2 Mean Fourth growing s eason Mean SYO SYl Summary No. 4. A v e r a g e d height (in inches) of tallest seedlings At end of Spruce Balsam Birch 1.60 1.47 1.57 1. 56 1. 53 1.69 1. 80 1.47 3.99 6.74 10.73 14.72 1. 54 1. 54 5.32 3. 20 2.70 2. 54 1. 90 1. 80 1. 52 9.72 11. 01 13.69 2. 80 1. 84 10. 55 4. 81 3.18 2. 08 1.13 12.26 13.68 3.93 1. 94 11.87 Seeded Year Second growing season SYO SYl SY2 SY3 Mean Thi rd growing seas on SYO SYl SY2 Mean Fourth growing season Mean SYO SYl Summary No. 5. At the end of Second growing season Th ird growing season Fourth growing season A v e r a g e d Height of tallest seedlings by site types Spruce Balsam Birch Site Type Site Type Site Type AD O AD O AD O SYO SYl SY2 SY3 1.70 2. 03 1.72 1. 60 1. 20 1. 51 1. 39 1. 56 2. 18 1.98 1.66 1.34 1.44 1.18 1. 93 1.37 6. 20 9. 96 11. 27 18. 10 2. 98 3. 50 8. 84 13. 60 SYO SYl SY2 3. 18 2. 98 3. 56 1.75 2. 88 2.46 2. 50 .99 1. 95 1.95 1.75 1.42 8. 53 12. 37 18.70 2. 94 11.76 15. 86 SYO SYl 5. 99 3. 11 3.64 3. 02 4. 13 1. 56 14. 19 19. 13 7.62 10. 56 Seeded Year 1.31 1.49