Dendroecological analysis of successional dynamics after fire in the Shakwak Trench, southwest Yukon Territory.

Abstract

This study investigates the succession following fire in a relatively dry area of the boreal forest, the Shakwak Trench, southwest Yukon. The postfire successional regime is determined by an analysis of age structure and composition of tree populations in stands of different ages. The dendroecological approach used in this study is based on the sampling of one plot in each of 11 fires ranging from A.D. 1844--1998. Picea glauca established 0--4 years after fire and reached a period of maximum establishment after 20--40 years. Populus tremuloides was generally recruited immediately after fire and was no longer present after approximately 20 years, at which point, the Picea glauca began to dominate. Salix spp. were found in all stages of succession, but decreased in abundance through time. Five chronologies that were developed from ring-width measurements of the older Picea glauca trees depict similar growth-ring patterns, suggesting a large-scale climate influence on all sites in the region. There is a weak relation between the variability of the tree-ring chronology and the establishment of Picea glauca seedlings. Regeneration of tree species after fire is primarily driven by biological influences rather than climatological ones.