2009 BES Annual Meeting Presentation and Poster Abstracts
Co-Authors: Peter Groffman Kathleen Treseder Weixing Zhu Adriel Leon
Abstract: Global atmospheric CO2 concentrations are increasing at historically unprecedented but ecologically gradual rates while air temperatures are warming and precipitation patterns are changing. Will increased atmospheric CO2 may stimulate productivity and increase sequestration of C into soil organic matter, providing a negative feedback on global warming. Or are forests C saturated or is C storage limited by other soil nutrients or moisture. Alternatively, warming may accelerate decomposition and deplete soil C. To determine if rural to urban gradients in atmospheric CO2 concentrations have influenced forest C storage we are measuring productivity (tree growth ring increments), historical atmospheric CO2 concentrations (via 14C depletion in tree rings) and soil parameters of the surface 15 cm (total C, N, and Pb, pH, and bulk density) in ten forested plots throughout the Baltimore metropolitan area. Our proxy for historical CO2 concentrations, a spatial gradient in tree ring 14C content, indicates a range in CO2 concentration across the rural to urban transect of 12 ppmv during 2005 to 2008. Forested plots in the eastern portion of the metro area tended higher CO2 concentrations than in the western portion. Preliminary results indicate that in non-nutrient limited forested plots (6 out of 10 plots), total soil carbon content is positively correlated to atmospheric CO2 concentrations. This lends support for the overarching hypothesis that terrestrial ecosystems will store more soil carbon in a world with greater atmospheric CO2 concentrations. This will be one of the first long-term (>20 years) tests of this widely hypothesized potential feedback on the accumulation of atmospheric CO2 and global climate change.