| Module 3 — Stand level components of biodiversity |
British Columbia Ministry of Forests |
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Index | Ministry Home Module 3, Part B — Wildlife trees — continued |
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Individual live tree retention |
Individual live tree retention has
four subheadings:
Even though it is the preferred leave strategy, not all blocks can accommodate wildlife tree retention in patches. Depending on site-specific factors (such as topography, wind exposure, stand age and structure, rotation length, silvicultural system and harvesting method) some locations may be better suited to individual tree retention as a wildlife tree management strategy. Individual live trees left as wildlife trees can contribute to the required WTP area retention (see Table 1-A and Table 1-B) on a basal area equivalency basis. However, simple stem basal area does not equate to patch area. (WTP — wildlife tree patches). Basal area equivalency is only about the amount of basal area. The context here is basal area equivalency is the amount of basal area that is dispersed compared to the amount of basal area in an unharvested patch of trees.
It does not mean the biodiversity or ecosystem functions are equivalent. In fact, the biodiversity value is almost certainly different. The value of residual basal area towards biological diversity relates to the desired objective. The diversity being provided by individual stems is different than that provided by a variety of vertical and horizontal structures, coarse woody debris, forest floor and special habitats found in a patch.
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Trees can be distributed
singly or in small clumps depending on the silvicultural system, operational
constraints (slope and topography, harvesting method), and proximity to other
habitat features (riparian areas, hardwood patches, gullies, rock outcrops).
Broad-leafed deciduous trees tend to be a preferred tree for nesting and feeding by many cavity excavators, and are less susceptible to windthrow in late autumn and winter when severe windstorms are more common, as a result these trees should be left on site. Advance regeneration can also be left on the block to provide some structural diversity |
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