Age structure and growth of the tree-seedling bank in subalpine spruce-firforests of south-central British Columbia

We examined the dynamics of the tree-seedling bank in old-growth, subalpine Picea engelmannii-Abies lasiocarpa forests in south-central British Columb ia by collecting all individuals <1.3 m tall within belt transects at two s ites (n = ca. 500 per site) and determining their height, basal diameter an d age. Seedlings were up to 149 y old. Regressions showed that spruce I-m t all averaged 65-y old and fir 92-y old, Age structures indicated that recru itment into the seedling bank was variable with time, but that individuals of both species occurred in almost all 5-y age classes. Regressions of heig ht and diameter vs, age had high predictability and showed that spruce grew more rapidly than fir. Allometric (height/diameter) relationships differed significantly between species; spruce had a much greater height/diameter r atio than fir. Seedlings accumulate gradually and persist for long periods in the seedling bank, thus forming a large pool of individuals that can pot entially respond to opening of the canopy.