Ungulates of the Elwha: Effects of Woody Debris on Feeding Behaviors in the Elwha Dam Restoration Zone

Our study focused on the effect of woody debris on ungulate browsing in recently re-vegetated areas of the Elwha river. While past studies have focused on patterns of ungulate browsing along the Elwha river, no study has focused on how woody debris might affect these patterns. The questions we set out to answer were: to what degree, if any, does woody debris prevent ungulate browsing of plants in the open areas along the Elwha river, in the restoration zones, and does the amount to which plants are surrounded by woody debris affect the degree to which those plants are browsed by ungulates. In our study, the dependent variable was the amount of plants at each of the sites that displayed signs of ungulate browsing. We measured two independent variables affecting the outcome of our variable of interest; these were the amount of woody debris obstruction at each of the sampled sites and the distance from the woody debris that the plants were located. We used stratified sampling to determine the sample sites along the upper reservoir area of the Elwha river. We used a rating system that ranged from one, the least amount of protection from woody debris, to four, the most amount of protection from woody debris to categorize the amount of woody debris obstruction at each of the sampled sites. Using a two-way ANOVA allowed us to see significant interactions between the different factors and their effect on the intensity that certain plants are browsed. The data shows significant interactions between the ungulate browsing intensity on plants, the distance plants are located from woody debris, and the level of protection woody debris provides. Our results will have important implications for the future of revegetation efforts in the Elwha River system as well as in future dam removal projects