Carbon cycle implications of forest biomass energy production in the Northeastern United States

Abstract

There has been enormous interest in the use of forest biomass as a component of the renewable energy portfolio of the northeastern United States. While often touted as an inherently carbon-neutral energy source, it has become clear that a wide range of factors need to be considered to evaluate the net carbon and climate impact of biomass energy production (Cook and Beyea 2000; Abbas et al. 2011; Schulze et al. 2012; Zanchi et al. 2012). Net growth in northeastern forests currently provides an important offset to fossil fuel emissions of greenhouse gases, but most studies predict that carbon sequestration rates in forests both regionally and nationwide will decline over the next 20-50 years (Hurtt et al. 2002; USDA Forest Service 2012). The decline in the magnitude of the annual net carbon sequestration in the US forests is believed to be a product of three main factors: a stabilizing or even reversal of the century-long trend of an increasing forestland base due to reforestation of abandoned farmland (Drummond and Loveland 2010), declining rates of net growth at the stand level because of forest maturation (Hurtt et al. 2002), and increasing rates of forest harvest (Radeloff et al. 2006). All of these raise important questions about the magnitude of the sustainable supply of biomass feedstocks from northeastern forests (Buchholz et al. 2011) as well as questions about the future of regional forest carbon stocks under new demand for biomass energy.