Carbon and nutrient implications of using forest biomass for bioenergy

Background/Question/Methods   Increasing interest in using forest material as an energy source brings greater focus on the implications of removing biomass on the size of carbon stocks in terrestrial ecosystems, as well as the sustainability of these removals.  Key issues needing to be examined to understand the implications of diverting increasing amounts of woody material to meet the energy needs of the US include net carbon emissions to the atmosphere, assumptions about carbon neutrality over the timeframes for which public policies are intended to reduce atmospheric concentrations of greenhouse gases, potential for depleting nutrient stocks as well as the availability of net primary productivity not already being utilized for human purposes and potentially available.  In many cases current public policy assumes that replacing fossil fuels with sustainably grown biomass results in reduced net emissions of carbon to the atmosphere over the next 20 years, yet this is often not the case.  The use of harvesting slash can alter this situation, but can raise questions related to rates of nutrient depletion, given that the slash has higher nutrient concentrations than boles. 

Results/Conclusions   I will outline a set of frameworks that allow for easy analysis of what harvesting regimes and ecosystems types can yield biomass that will produce climate benefits sustainably.  Overall it is critical that ecologists and foresters apply what they know about biogeochemistry and succession associated with forest harvesting to identifying how much biomass can reasonably be utilized for bioenergy and where that can be done with acceptable impacts on ecosystem structure and function.