Increased levels of forestry BMPs reduces potential sediment delivery from clearcut harvests in the southeastern U.S.
Forestry Resources Association Technical Release 22-R-12
BMP Series: Article 1 out of 3
Brent S. Hawks, W. Michael Aust, M. Chad Bolding, Scott M. Barrett, and Erik B. Schilling (NCASI)
Sediment is the most common nonpoint source pollutant impacting surface water in the U.S. Forestry Best Management Practices (BMPs) can reduce sedimentation from harvesting operations, assuming that recommended practices are properly implemented as needed. Common BMP guidelines involve minimizing the grade and area of forest roads, utilizing ground surface cover, installing and maintaining water diversion structures, and maintaining Streamside Management Zones (SMZs) adjacent to streams. However, few studies have examined sediment reductions due to different levels of forestry BMP implementation. The objective of this study was to provide estimates of sediment delivery to streams generated by recent clearcut harvests and associated road networks at three BMP implementation levels (BMP–, BMP-standard, BMP +). BMP– (90%) represent low, average, and above-average levels of implementation of recommended practices. BMP audit questionnaires were collected from the 13 Southeastern states (Alabama, Arkansas, Florida, Georgia, Kentucky, Louisiana, Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, and Virginia). At 108 recent clearcut sites in the Southeastern U.S., we evaluated BMP implementation and estimated erosion using the USLE-Forest Model (tons ac-1 yr-1). Data were collected at five operational features including stream crossings, haul roads, skid trails, decks/landings, and the area where trees were felled referred to as the “harvest area.”
Additionally, sediment delivery data were obtained in the Mountain, Piedmont, and Coastal Plain Regions of Virginia and North Carolina at over 180 silt fences trapping sediment from the same operational features. State BMP audits, erosion estimates, sediment delivery data, and annual clearcut areas (ac yr-1) were obtained from the US Forest Service’s Forest Inventory and Analysis (USFS FIA) Program and subsequently combined to estimate total sediment delivery from clearcut harvests in the Southeastern U.S.
This research received financial and logistical support from the National Council for Air and Stream Improvement, Inc. (NCASI), the Sustainable Forestry Initiative (SFI), the Virginia Tech Department of Forest Resources and Environmental Conservation, the Virginia Tech Forest Operations and Business Research Cooperative, and the USDA National Institute of Food and Agriculture McIntire Stennis project 7001490. More information about how BMP implementation influences sediment delivery across the southeast is published in Forest Science (https://doi.org/10.1093/forsci/fxab057). Additionally, the study that examines how BMP implementation influences erosion in the southeast is published in the Journal of Environmental Management (https://www.sciencedirect.com/science/article/pii/S0301479721024737?via%3Dihub). The full study with more detailed methodology and results can be found at https://vtechworks.lib.vt.edu/handle/10919/109423.