| Emerging public interests to utilize forest woody biomass as an alternative feedstock accompanies a concern about potential nutrient depletion by increased woody biomass extraction. This study was conducted to investigate the long-term impact of intensive biomass utilization on site productivity and forest condition in the northern Rockies. The 1974 Forest Residues Utilization Research and Development Program site at Coram Experimental Forest of western Montana were revisited, and responses from individual tree to ecosystem level were measured. The experiment was designed to address the effect of biomass utilization intensity (high, medium and low) combined with prescribed broadcast burning treatment following conventional regeneration cuttings (i.e. shelterwood, group selection, and clearcut).;Planted trees showed no differences in height, dbh, and volume growth, as well as the individual's physiological traits such as mean leaf area, growth efficiency, and foliar C and N concentration. At the stand level, metrics including basal area, density, and quadratic mean diameter for regenerated trees production were affected by regeneration cutting treatment. However, the biomass utilization intensity was not a significant factor for the regenerated tree biomass production. Initial impacts of biomass harvesting on understory shrub vegetation were significant, but the shrub vegetation rapidly recovered within 10 years after harvesting, and shrub biomass, species composition and diversity 38 year after harvesting were unaffected by biomass utilization intensity. Analysis at the ecosystem level, encompassing the mineral soil layer to the overstory tree layer, yielded a consistent result, concluding that there is no evidence for the adverse long-term impact of intensive biomass utilization on site productivity. |
