Windthrow impacts in riparian leave-strips

摘要

The riparian buffers experiment at the University of British Columbia research forest was com-menced in 1998. In this experiment Om buffer (fully harvested), 10 m, 30 m and unharvested(control) treatments were replicated three times within 70 year old uniform structured standsdominated by western hemlock (Tsuga heterophylla). Approximately 15 % of the retained treeswere windthrown in the 10 m buffer treatment, and 10 % in the 30 m wide treatment, primarilyin the first 2 years following harvest of adjacent timber. Windthrown trees were smaller than theaverage tree. Stand self-thinning is an additional source of mortality, particularly in the controland 30 m buffers. Eight years after harvest, 90% of the windthrown trees were still suspendedabove the stream channel. The area of exposed soil is related to the diameter and number ofuprooted trees, but only 14 % of uprooted trees were in a position to deliver sediment to thestream channels. Results of this study have been integrated into ForestGALES_BC to modelwindthrow impacts on streams.