| Utilization of renewable resources for energy in the United States has increased substantially over the past decade. These increases have been driven by energy policy aimed at reducing dependence on foreign oil, boosting economic development, and curbing fossil fuel emissions. In recent years, state governments have passed laws mandating further reductions in energy consumption and greenhouse gas emissions, and increases in energy conservation and use of renewables. Such legislation and pending federal action has led to renewed interest in the use of forest-derived biomass for energy production. There are a variety of sources of forest-derived biomass in the Lake States and much debate over the carbon costs or benefits associated with the utilization of this material for energy. The aspen forest type is dominated by the most commercially utilized tree species in the region (Populus tremuloides and to a much lesser extent, P. grandidentata and P. balsamifera ) and occupies more than 10 million acres of timberland in Michigan, Minnesota, and Wisconsin. Aspen is a short-lived, fast-growing tree species, which typically regenerates from adventitious suckers following harvest or stand-replacing disturbance, making it ideally suited for biomass production. This dissertation describes: (1) the status and trends of aspen-dominated ecosystems in the Lake States, (2) an analysis of biomass production potential in native and hybrid aspen communities in northern Minnesota, (3) a model framework for the estimation of carbon flows associated with the procurement and utilization of harvest residues for energy, and (4) the development of a spreadsheet-based model for rapid estimation of biomass availability. |
