Harvesting of biomass from forests as a biofuel feedstock shows promise for reducing use of fossil fuels. Some scientists suggest that forest-derived biofuels are carbon neutral, that is, they do not add to atmospheric carbon dioxide. However, if not done cautiously, biomass harvesting may come at a cost of reduced productivity of the soil and regenerating forest, compromising the sustainability of this practice. Forest Service, U.S. Geological Survey, and University of Minnesota researchers used the Lake States Long-Term Soil Productivity (LTSP) study to examine productivity responses to biomass harvesting. This study capitalizes on the 20-plus years of detailed data on soil nutrients and tree growth from the LTSP study. Results indicate that a one-time removal of trees and slash (branches, twigs), without disrupting the forest floor, does not appreciably lower soil carbon or nitrogen or biomass growth of regenerating trees, particularly on nutrient rich soils. However, evidence suggests that functional richness and evenness of plants may decline, and that lower nutrient levels and more frequent harvests on short rotations might greatly reduce tree growth, particularly on sandy soils. This project is helping managers in the Lake States understand how they can use woody biofuels from their forests without compromising ecosystem sustainability.