Carbon Stocks and Sequestration: How much do we know?

As anthropogenic CO¬¬2 emissions in America increase, both Washington D.C. and state governments look for ways to offset those carbon increases. Our forests provide an opportunity for carbon sequestration, assuming well-informed and deliberate management practices. Accurate spatial and temporal estimates of carbon stocks are integral to developing wise management practices. Spatial carbon stock estimates are often represented in carbon maps while temporal estimates are calculated using computer models. These maps and models come from a variety of sources such as the United States Department of Agriculture (USDA), the Forest Service (FS), and independent researchers. Here we evaluate the Forest Service's Forest Vegetation Simulator (FVS) to determine its sensitivity to input changes as well as its predictive ability over time. We analyze field data collected from a site in the San Juan National Forest. This site was clearcut in 1920, allowing us to model a complete regrowth over 90 years. Using biomass-to-carbon equations, we compare present-day carbon storage to FVS model projections. Finally, we look at the Forest Inventory and Analysis (FIA) database and a spatial carbon map developed by researchers at the University of Colorado to assess the validity of landscape-scale estimates. Results indicate that the four spatial carbon estimates we use vary by only 25% while the temporal carbon estimates diverge radically from field data. Knowledge of carbon uptake rates is one of the most pressing questions in atmospheric and ecological science. It is imperative that carbon models be improved to achieve this goal. Spatial and temporal comparisons such as the one conducted here are needed to provide the groundwork for model development. Carbon estimates for Shearer Creek in the San Juan National Forest based on four different methods: the Forest Vegetation Simulator, the USDA Forest Inventory and Analysis Database, a spatial carbon map from the University of Colorado, and my own field data taken in the summer of 2012.