The development and use of best practices in forest watersheds using GIS and simulation models
Forest watersheds provide timber and water, wildlife and fisheries habitat, and recreational opportunities. However, not an entire watershed is equally suited for each activity. Steeper slopes may be better left forested and used for wildlife habitat, while more gentle slopes of the watershed could be used for timber production. Logging steep slopes can lead to soil erosion that can seriously degrade stream water quality and reduce long-term site productivity. Best Management Practices (BMP’s) are forest practices designed to minimize negative environmental impacts caused by human forest use. The difficulty in developing BMP’s arise when multiple objectives (e.g., improved timber production, water quality, and recreation) are applied to a single watershed. The objective of this research was to maintain long-term stream water quality, fisheries, and timber productivity, while minimizing soil erosion and negative water quality impacts associated with forest management. Computer simulation models and a geographic information system (GIS) were used to create management scenarios that test how a watershed could best be managed to maximize its multiple potential use. The authors used an 1143 ha forest watershed in Western North Carolina, USA. Basin elevations range from 920 m to 1655 m. The scientists combined a GIS, three desired future conditions, the Universal Soil Loss Equation (USLE), and a terrestrial transport model to predict BMP’s for the watershed. Through the use of a GIS, model predictions of sediment production and transport can be spatially distributed across the watershed and displayed as map outputs of soil movement. This paper demonstrates how land managers could identify BMP’s using a GIS-based modeling system. Once identified, alternative management scenarios can be developed to assess the cumulative effects of management practices on forested watershed health and sustainability.