Downed wood associated with roundwood harvest, whole-tree harvest, and unharvested stands of aspen in Wisconsin

Public demand for alternative energy sources, including bioenergy and biofuels, is resulting in increased demand for woody biomass from forest ecosystems. Forest management practices may change to meet the increased demand for woody biomass through the intensification of timber harvest, which includes shortened rotation times and increased removal of woody material. Our goals were to provide empirical data on residual wood retained on site following operational harvest of aspen stands, including quantification of woody debris of all size classes and the development of quantitative models to express the relationship between coarse and fine woody debris. Aspens stands with roundwood harvest (125.71 +/- 20.79 m(3)/ha) contained more total downed wood than stands with whole-tree harvest (75.54 +/- 23.70 m(3)/ha), and both harvest types contained more downed wood than unharvested, mature aspen stands (40.90 +/- 11.60 m(3)/ha). Notably, harvested stands contained on average more fine woody debris (58.31 +/- 15.86 m(3)/ha) than coarse woody debris (39.89 +/- 20.48 m(3)/ha). We found strong support for the model predicting volume of fine woody debris from volume of coarse woody debris, harvest type, and county. This tool will enable managers to estimate volumes of fine woody debris when field measurements of fine woody debris are too labor intensive. Our results indicate that recently harvested stands of aspen contain downed wood that could lend itself to intensification of timber harvest as markets for woody biomass increase. However, these estimates also highlight that substantial amounts of woody material have historically remained on site as wildlife habitat and nutrient inputs into regenerating stands, and thus this woody material may be necessary for long-term forest sustainability. Published by Elsevier B.V.