Retention Patches: Windthrow and Recruitment of Habitat Structure 12-16 Years Post-Harvest.

Abstract

I examined wildlife tree, coarse woody debris, and windthrow characteristics of 157 retention patches left in harvested areas of the Kispiox (mostly ICHmc), and Bulkley/Morice (mostly SBSmc, ESSFwv/mc) Timber Supply Areas in the early to mid 1990s. Patches added substantially to important habitat elements in the harvested areas. Windthrow rates were moderate, totalling about 11% and 19% of the post-harvesting standing tree basal area (after 12-16 years post-harvest) in the Kispiox and Bulkley/Morice samples respectively. Most of the windthrow occurred in the first few years post-harvest, and then dropped to background levels. I conclude that, overall, windthrow is not a significant issue. If, however, minimizing windthrow is a goal then previous rule-of-thumb criteria still apply: create larger patches (>1 ha) of minimum perimeter, oriented to minimize perimeter exposure to prevailing winds and place patches on topographically sheltered sites.