Response of seedlings and saplings to canopy gaps in coastal old-growth forests.

摘要

Fine-scale disturbances involving the death of one to a few trees create gaps in the forest canopy and, where large-scale disturbances are rare, exert a dominant influence on community and population dynamics. I examine the natural regeneration and recruitment of seedlings and saplings following fine-scale, gap forming disturbances in old-growth stands within the Capilano, Seymour and Coquitlam River watersheds. I compared the abundance of western redcedar, western hemlock, and Pacific silver fir seedlings and saplings between plots located within and adjacent-to 20 gaps of known date of origin. I also destructively sampled seedlings and saplings of each species and applied dendroecological methods to determine the age of each sample, and to elucidate patterns of suppression and release in radial growth. My results support the paradigm of gap-scale canopy replacement. Seedlings and saplings were more abundant in gap versus forest environments, and exhibited increased rates of establishment and radial growth.;Keywords: canopy gap; temperate rainforest; Tsuga heterophylla; Abies amabilis; Thuja plicata; forest dynamics