Edge Effects in High - elevation Forests at Sicamous Creek Extension Note 62

Edge effects are increasingly important in British Columbia forests, as cutblocks become smaller and harvesting options with retention patches are more commonly used. This note summarizes edge effects for  ecosystem variables, including microclimate, soil chemistry, snow depth, windthrow, regeneration, vegetation, and animals, at the Sicamous Creek Silvicultural Systems project in a high-elevation ESSF forest. Physical variables such as soil temperatures and snowmelt showed small edge effects up to – m from forest–cutblock edges. Effects on plants and animals typically extended at most – m from the edge, except for windthrow, with effects more than  m into the forest along some edges. Substantial windthrow adjacent to large openings may also lead to “edge creep,” where edge effects extend into the forest over time, affecting many ecological values. Bryophytes and spruce grouse showed increasing edge effects in the initial post-harvest years. Because edge effects from uncut forest did not extend far into cut areas, small openings (< ha) interspersed with narrow leave strips or numerous small retention patches are likely most effective for retaining “forest influence” throughout a cutblock. Large retained patches and wide corridors will still be important at the landscape scale, but small patches also have considerable conservation value, provided that windthrow is managed.