Spatial-Temporal Dynamics of Brant Herbivore Interactions and Ecosystem Processes in Coastal Tundra of the Yukon-Kuskokwim Delta in Western Alaska

University Of Alaska Fairbanks Campus, Fairbanks AK

Investigators

Abstract

Abstract OPP-99-85831 Sedinger This project is collaborative with the University of Alaska and Colorado State University. It is being funded by the Office of Polar Programs, Division of Environmental Biology and Ecology, and Ecosystem Studies. Over the next five years, the Principal Investigators will address spatial-temporal variation in plant herbivore interactions and associated ecosystem processes in a goose grazing system in coastal tundra of the Yukon-Kuskokwim (Y-K) Delta, Alaska. Their fundamental hypothesis is that interactions between herbivores and early successional states are tightly coupled, such that herbivores require these early successional states for successful production of offspring. Furthermore, herbivores not only maintain, but are capable of creating these early successional states by grazing associated activities. Moreover, spatial/temporal complexity in vegetation patterns and the response of herbivores to habitat patches introduce substantial complexity into succession, ecosystem processes and herbivore population dynamics. The Principal Investigators will examine four inter-linked hypotheses: 1) the influence of herbivory on succession; 2) the influence of herbivory on nutrient cycling processes; 3) time lags in the successional response of vegetation to herbivory; and 4) the role that temporal-spatial patterns in herbivory play in determining ecosystem state. This proposal builds on a 16-year study of nutrition and other factors other factors on demography of the black brant (Branta bernicla nigricans) geese that nest on the coast of the Y-K Delta, and on seven years of research on vegetation/ ecosystem response to herbivory. This study takes advantage of a large sample of individually marked brant that will provide the team with an unprecedented opportunity to measure demographic responses of herbivores to the quality and quantity of their food. Intensive herbivory sophisticated experiments on the effects of herbivory on soil processes. The Principal Investigators will use a modified version of a spatial ecosystem model (SAVANNA) to test hypotheses what could not otherwise be examined about the relationship between spatial patterns of herbivory and ecosystem state. SAVANNA will be directly linked to a goose population model to fully incorporate herbivore dynamics into their hypothesis testing, and the field experiments are designed to allow them to parameterize SAVANNA for coastal tundra. Modeling will also serve to guide full integration of their field experiments and monitoring across trophic levels. The current project also will link research on the same population of geese and associated wetland habitats in Mexico. This may be the first study to fully integrate dynamics of soil processes, vegetation and herbivory in an ecosystem context at such a broad spatial scale.