Carbon Content within a Longleaf Pine Ecosystem: the Effects of Land Use and Soil Type On Carbon Concentration.

Increasing atmospheric concentrations of CO₂ and proposals for possible C cap-and-trade systems have led to interest in C sequestration in forest soils and vegetation to provide a biological sink for atmospheric CO₂.  Effects of land use and land cover on C storage in different soil types are inadequately quantified as are means for estimating soil C across landscapes.  This work compares the contents of soil C among differing land cover and soil types on the Dougherty Plain of the upper coastal plain of Georgia, USA, with a particular interest in longleaf pine (Pinus palustrus) woodlands that regularly managed with prescribed fire. C contents of dominant soil great groups and land cover types were compared.  Samples were collected from 821 long term monitoring plots from depths of 0-5, 5-20, and 20-50 cm.  They were analyzed for total C and N, and were used to determine dominant effects upon soil C across the landscape using multivariate methods and GIS based approaches to soil mapping.  Results depict soil C concentration to vary mainly among land cover types, with depletion primarily influenced by agricultural land use history.  Median values for agricultural sites were 1.23% while values for sites with no agricultural history range from 2.9% (deciduous wetland) - 1.8% (grassy pond).   C concentrations in soil surface horizons within areas dominated by longleaf pine (μ 1/2(X) = 2.24 and IQR = 1.12) are similar to those in areas dominated by hardwood species (μ 1/2(X) = 2.25 and IQR = 1.37)   with more hardwood litter accumulation being the major difference.  C concentration of varying longleaf pine management regimes is also of interest.  Regular prescribed burning is vital to the health and growth of longleaf pine dominated ecosystems.  This study also compares the C concentrations of burned suppressed sites, restored sites, current agricultural sites and sites that have had extensive hardwood removal. Black carbon quantification is also of interest as sites that have been burn suppressed are being compared to those that receive regular burn prescriptions.