Biomass Harvesting Effects on Soil Physical Properties in the Coastal Plain of North Carolina
Biomass harvesting offers opportunities to produce portions of US energy demands from renewable resources, yet there are concerns that biomass harvesting could deplete nutrient reserves, increase potential for soil erosion, or lead to problems associated with increased forest trafficking. On intensively managed loblolly pine (Pinus taeda) plantations on relatively flat coastal plain terrain, nutrient demands may be met with fertilization and soil erosion is of lower concern. However, soil disturbance associated specifically with coastal plain biomass harvests for renewable energy production have not been widely documented. Soil disturbance classes and physical properties were examined on three intensities of biomass harvesting on a 52 ha loblolly pine plantation in the North Carolina coastal plain. Study objectives were to determine if biomass harvesting intensity and associated traffic were correlated with changes in soil physical properties or visual soil disturbance classifications. Harvesting intensities included in the designed operational study were: 1) roundwood removal only, 2) integrated harvest including roundwood removal and biomass production, and 3) chip only harvest where all trees were removed and chipped for biomass. Harvesting treatments were replicated 3 times each (9 experimental units) using a randomized complete block design. Soil properties were evaluated pre- and post-harvest to determine harvesting related impacts. Results indicate that most soil physical properties were not significantly altered due to harvest level with the exception of small deck areas. These data indicate that biomass harvesting did not result in visual or physical changes to soil properties as compared to traditional harvests and indicate that standard best management practices may be adequate to address biomass harvesting issues for similar sites.