Examination of long-term soil development and phosphorus dynamics in a hypermaritime chronosequence, Calvert Island, British Columbia, Canada

This thesis examines soil development, phosphorus (P) dynamics and ecosystem succession in an aeolian sand dune chronosequence spanning 10,760 years on Calvert Island, in hypermaritime coastal British Columbia, Canada. After 100 years of soil development, thick forest floors have developed (~28 cm), and after ~3,500 years mature Podzols have formed with cemented placic and ortstein horizons. With increasing soil age, mineral soil total P declines linearly and organic P forms become increasingly dominant, with glycerophosphates dominating organic horizons, and inositol hexakisphosphates and DNA dominating mineral horizons on the older sites. After 7,000 years, ecosystem retrogression – a long-term decline in biomass – is suggested by reduced tree basal area and a shift towards shrubby, more stress-tolerant species such as Pinus contorta var contorta and Tsuga mertensiana. Retrogression in the Calvert Island chronosequence is most likely caused by formation of cemented horizons and declining soil P reserves, though further investigation is needed.