Technical Bulletin No. 0992: Relationships Between Intensive Biomass Production and Biodiversity in North American Forests – A Literature Review
Biomass feedstocks may be produced in forests through a variety of practices such as thinning and fuels treatments, use of harvest residues including fine (foliage, small limbs and trees) and coarse woody debris (snags and downed logs), establishment and harvesting of short-rotation woody crops, and harvesting of natural biomass or intercropped herbaceous plant species between crop tree rows in intensively managed stands. When applied across a broad spatial extent, intensive biomass production in forests, which support a large proportion of biodiversity, has the potential to alter species composition, nutrient cycling, and overall biodiversity. However, potential effects of biomass harvesting on biodiversity are not well known. To examine potential impacts and assess information gaps, we used a literature review and meta-analyses of manipulative and observational studies to assess potential biodiversity responses to practices associated with intensive biomass production systems in North American forests. Biodiversity responses varied among taxa and production systems reviewed. Most taxa responded positively to thinning treatments. Reducing coarse woody debris will likely decrease bird diversity, but other taxa may not respond strongly. If reductions in coarse woody debris from actual harvests are less than the 70 – 95% used in experimental studies, then overall biodiversity responses may be minimal. Short-rotation woody crops may have lower diversity of birds and mammals than managed forests, but there is considerable uncertainty. We found no studies of biodiversity response to intercropping of native, warm season grasses in commercial forests. A small number of studies or strong geographic bias in available studies for some practices increased uncertainty about consistency of observed responses.