Optimizing forest and road networks to minimize sediment loads and to protect somonid habitat in the face of climate change

Research Sponsored By: USDI US Geological Survey
Principal Investigator: Sándor F. Tóth
Project Description
Forest roads provide access to timber, woody biomass and outdoors recreation. They facilitate the detection and control of wildfires and invasive forest pests. Forest roads also disrupt wildlife habitat, cause sediment delivery to streams and compromise fish habitat. They account for the largest environmental and economic cost of all forest operations. In practice, timber harvesting and road construction decisions are treated independently leading to missed opportunities for fixed cost savings and reduced impact on sediment and fish. We developed a spatial optimization model that integrates the two sets of decisions. Using the Washington State Department of Natural Resources’ Olympic Experimental State Forest, we showed that the new model can save hundreds of thousands of dollars in net revenues with only 85% of the length of the current network in place during the next one hundred years. In this study, we will develop a proxy function between the projected sediment production of a given road segment and the resulting quality and quantity of salmonid habitat under different climate scenarios. We will start with a literature review on the subject and analyze how the alternative models that had been documented could be imbedded in our integrated decision model. Spawning salmonids lay their eggs in nests called redds in the gravel of streams. Since the size of the redds is specific to the species, the impact of various particle size profiles associated with the projected sediment loads on fish habitat will also vary with species. Particles of a certain size will infiltrate into some redds to a greater extent than others. We will evaluate the literature on these differential effects as well as the role of other factors such as stream temperature, velocity and depth. The short-term goal of this project is to develop a model for predicting the effects of roads and climate on sediment and stream habitat. For sediment load projections, we will use the USDA’s Water Erosion Prediction Project (WEPP) model, the Washington State Department of Natural Resources’ (DNR) Road Surface Erosion Model (WRSEM), as well as climate change scenarios. Our long-term goal is to incorporate the proxy function in our integrated harvest and road scheduling model to explicitly account for fish habitat.