Influence of Residue Management On Soil Chemical Properties and Nutrient Flux in Forests Harvested for Woody Biomass.

As the demand for energy increases, alternative energy sources such as woody biomass are being encouraged to play a larger role in energy production. Because of the potential adverse effects of woody biomass harvest to soil nutrient pools and overall soil quality, the Missouri Department of Conservation (MDC) has developed Best Management Practices (BMPs) to retain coarse woody residues associated with biomass harvesting to retain nutrient capital and sustain forest productivity. However, these BMPs remain untested. The objectives of this study are to: (1) investigate changes in soil nutrient flux and soil solid phase nutrient concentrations under conditions representative of various types of woody biomass harvest and, subsequently, different residue retention levels; and (2) evaluate the efficacy of current BMPs for woody biomass harvest to determine if they adequately protect soil nutrients and the sustainability of forest growth in the Ozark Highlands. The research to be presented was conducted at MDC’s Indian Trail Conservation Area near Salem, Missouri. The eight treatments being investigated include Missouri’s 1/3 harvest residue retention BMP for thinning and commercial biomass harvests and other alternative harvest scenarios. Changes in plant available nutrients have been monitored using Plant Root Simulator (PRS) ion exchange membrane probes provided by Western Ag Innovations. Preliminary data indicates greater nutrient supply rates in the clearcut treatments compared to the intermediate thinning and control treatments for specific ionic species measured. Additional work on treatment effects to bulk soil chemical properties will also be discussed. This research will enhance our understanding of nutrient cycling in a forested ecosystem following a woody biomass harvest; which will aid in maintaining sustainable nutrient concentrations and long-term site productivity.