Effects of spatial scale on forest carbon accounting

C.S. Galik and R.C. Abt are the authors of an important new report titled The Effect of Assessment Scale and Metric Selection on the Greenhouse Gas Benefits of Woody Biomass. The report has been posted online by Duke University’s Nicholas School for Environmental Policy Solutions at http://nicholasinstitute.duke.edu/climate/.

The report demonstrates that spatial scale of analysis can have major effects on models of the “carbon footprint” of biomass energy systems. For example, results of plot-level analyses in this study were inconsistent with results of analyses at larger spatial scales. The abstract follows.

“Recent attention has focused on the net greenhouse gas (GHG) implications of using woody biomass to produce energy. In particular, a great deal of controversy has erupted over the appropriate manner and scale at which to evaluate these GHG effects. Here, we conduct a comparative assessment of six different assessment scales and four different metric calculation techniques against the backdrop of a common biomass demand scenario. We evaluate the net GHG balance of woody biomass cofiring in existing coalfired facilities in the state of Virginia, finding that assessment scale and metric calculation technique do in fact strongly influence the net GHG balance yielded by this common scenario. Those assessment scales that do not include possible market effects attributable to increased biomass demand, including changes in forest area, forest management intensity, and traditional industry production, generally produce less favorable GHG balances than those that do. Given the potential difficulty small operators may have generating or accessing information on the extent of these market effects, however, it is likely that stakeholders and policy makers will need to balance accuracy and comprehensiveness with reporting and administrative simplicity.”