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Large Herbivores and Plants: Consequences of Interactions and Feedbacks
Terry Bowyer, Idaho State University, Pocatello, ID, Kelley M. Stewart, University of Nevada Reno, Reno, NV and John G. Kie, Idaho State University, Pocatello, ID
We review basic interactions among plants and large, herbivorous mammals. We begin with traditional views of plant-animal interactions, including the restructuring of plant communities based on high population density of animals, their foraging behavior, and resulting shifts in plant species composition. We examine feedbacks from reduced forage availability and quality resulting from increased population density on the dietary niche breadth of large herbivores. We also consider effects on nutritional condition of large herbivores and subsequent effects on their population dynamics. We follow this review with a description of positive effects of large herbivores on plants and their ability to serve as a keystone species, including the processes of herbivore optimization, and enhanced nutrient cycling. Herbivores are not randomly distributed across the landscape and factors that influence their local densities have profound effects on ecosystem structure and function. We discuss factors that hold potential to alter the distribution of large herbivores, including reasons underpinning sexual segregation, selection of birth sites, and risk of predation. Finally, we discuss how our knowledge related to the distribution and population dynamics of large herbivores could aid in management actions.