Long-Term Biomass Harvesting Effects on Forest Productivity under Three Silvicultural Systems in the Northern Rocky Mountains

Recent rising public concerns about climate change and increasing energy costs have led to the need to re-evaluate forest biomass as an alternative energy feedstock. Biomass harvesting could potentially impact ecosystems in various ways, including site productivity and forest stand dynamics. Since these issues influence decision-making, the effects of biomass utilization are primary issues not only for silviculturists but also forest engineers. Yet our understanding of long-term effects of biomass removal remains limited. Better understanding is needed of the effects of biomass utilization on forest composition, structure, and productivity. This study revisits a 1974 forest harvest and biomass utilization research program in mixed-conifer stands at Coram Experimental Forest in northwestern Montana. Four harvest utilization standards (combined with prescribed burning treatment) were established with two replications under three harvesting systems (shelterwood, clearcut and group selection) via a running skyline yarder. This study will examine the consequences of biomass utilization and harvesting system on 1) the physiological productivity of individual trees, 2) stand productivity, 3) vegetation structure and composition, and 4) regeneration dynamics. In combination with a related study of soil responses, this study will provide a comprehensive understanding of the effects of biomass utilization and harvesting treatments on above-ground and below-ground forest condition and productivity.