Soil Carbon Monitoring Plots In Vermont's Sustainably Managed Forests.

Sustainable harvesting for biomass relies on understanding and maintaining site quality. Increased demands will increase harvesting and site disturbance, potentially reducing long-term storage of carbon. Information is scarce on current forest soil stores of carbon and even less information exists on forest management effects on these stores. Our project goal was to establish reference plots in Vermont on actively managed forested lands. We selected 18 locations representing the major forest soil types and forest communities (northern hardwood, rich northern hardwood and lowland red spruce-balsam fir).  Sites included State and Federal lands, town forests and plots owned by non-profit organizations.  Plots were intensively sampled by soil horizon and depth increment to bedrock or dense till. Total soil carbon, including the forest floor, ranged from 43 to 193 Mg ha^-1. Above-ground live-tree carbon stores had a similar range of 62 to 180 Mg ha^-1. The distribution of carbon in the soil profile was affected by past land-use and an Ap (plow layer) horizon was often present. Extensive measurements of the forest floor showed that thickness varied widely, between 1 and 11 cm, again likely a result of previous land-use. This near-surface carbon is more directly susceptible to harvesting impacts from site disturbance. Results (www.uvm.edu/~soilcrbn) are being used to inform land managers and the public, and as a baseline to investigate changes after harvest activity.