The Ecological Impact of Using Logging Residues for Bioenergy
Policy makers at all levels of government are seeking alternative energy sources in order to reduce carbon (C) emissions and increase energy security. This has focused considerable attention on bioenergy. Federal policy has primarily emphasized energy produced from corn and other crops (Malmsheimer et al. 2008), but utilizing agricultural energy sources may actually result in a net increase in greenhouse gas emissions once processing, fertilization, and land-use change are included (Fargione et al. 2008, Searchinger et al. 2008, Melillo et al. 2009). Alternatively, many have argued that forest biomass could provide a large source of low-emissions bioenergy in the U.S., as it already does in much of Europe (Malmsheimer et al. 2008, Richter et al. 2009). Beyond a reduction in greenhouse gas emissions, use of forest biomass for energy production
would provide expanded revenue for rural communities, better energy reliability than wind and solar, and substantially lower polluting emissions of sulfur dioxide and nitrous oxides than coal (Malmsheimer et al. 2008, Dymond et al. 2010, Zhang et al. 2010). While the use of saw-logs and pulpwood for bioenergy is unlikely to be economical (Malmsheimer et al. 2008), branches and other logging residues from U.S. sources could supply energy equivalent to 145 million barrels of oil per year (Perlack et al. 2005). However, there has been little research toward understanding whether the management of forests for bioenergy will reduce forest productivity and increase forest greenhouse gas emissions (Lattimore et al. 2009). Further, the public is hesitant to embrace forest bioenergy, in part because there are few American examples of its successful utilization (Richter et al. 2009). In order to
improve both the scientific and public understanding of forest bioenergy, we propose a five year study of a model forest bioenergy system at the University of Idaho. This system would use residues from logging operations conducted at the University of Idaho Experimental Forest (UIEF) to supply the University of Idaho Steam Plant, which is already equipped burn forest biomass. The research project would compare three alternatives: (1) harvested sites with residues collected for bioenergy, (2) a "business as usual" approach, with residues removed from harvested sites through prescribed fire, and (3) un-harvested sites. First, this research design will allow us to measure bioenergy harvest effects on greenhouse gas emissions (CO2, CH4, N2O) relative to conventional regional forestry practices and undisturbed stands. Second, we will use this design to study how bioenergy harvest affects
nutrient availability and forest regeneration, using this information to model future forest productivity and assess questions about sustainable bioenergy management. Finally, we see this project as a chance to present a scientifically-oriented case study of regional forest bioenergy utilization.