Collaborative Research: Asynchrony in the timing of goose-vegetation interactions: implications for biogeochemical cycling in wet sedge tundra

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Terrestrial high-latitude ecosystems are experiencing dramatic increases in temperature, changes in precipitation, and advancement of the growing season with important implications for trophic interactions. Uncoupling of the temporal relationships between migratory animals and the phenology of the forage they rely on for energy, nutrition, and rearing of young is one of the most glaring consequences of these changes. Furthermore, herbivores in high latitudes are likely to mediate biogeochemical responses to climate change substantially altering ecosystem function. However, little is known about how changes in the synchrony of herbivore-vegetation interactions will influence biogeochemical cycles.This project will be conducted on the Yukon-Kuskokwim (Y-K) Delta in western Alaska, where there is strong evidence that climate change is driving temporal decoupling of the evolved linkage between the phenology of plants and the timing of goose migration. There is an urgency to the research because: some of the most rapid climate changes in the world are underway in Alaska, leaving migratory geese and the ecosystem processes they influence vulnerable to new conditions, and with the rapid advancement of the growing season, migratory goose feeding ecology is lagging substantially, threatening an irreplaceable subsistence resource for Native communities.The overall research objective is to quantify how an advancing growing season and changes in the synchrony of vegetation-goose interactions alter the magnitudes and patterns of C and N cycling in the Y- K Delta. Two specific questions will be addressed with an experiment: How does the timing of plant growth interact with goose arrival time to alter summer-long magnitudes of plant production, foliar chemistry, and N availability; and, How does the timing of plant growth interact with goose arrival time to alter summer-long magnitudes of net ecosystem CO2 exchange, gross ecosystem photosynthesis, and ecosystem respiration? SAVANNA-YK, a biogeochemical model that considers grazing a critical control on vegetation and trace gas processes in the Y-K Delta, will be used to predict how these ecosystem processes and plant-herbivore interactions will continue to change, altering the nature of ecosystem processes and landscape dynamics in years to come.The intellectual merit of the research is three-fold: The focus on phenologic decoupling of migratory birds and their primary forage on ecosystem biogeochemical cycles is the first of its kind. More specifically, the research is the first to investigate how the timing of herbivory interacts with plant phenology to affect biogeochemical cycles compared to other programs that have focused on the presence or absence of herbivores and/or on herbivore density effects on these cycles; The research is the first to take an experimental approach to the issue of trophic mismatch in the western Alaskan sub-Arctic while integrating these findings with forecasting ecosystem models tailored to wet sedge systems of the north. This combination allows investigation into how climate change effects on herbivore-vegetation interactions will influence large spatial scales in years to come; and The research focuses on plant species that are critical to migratory geese, while other northern studies focusing on climate change effects have focused on tundra plant species that are not critical to migratory bird foraging ecology.The broader impacts of the research will be realized throughh several activities. First, a citizen- science observatory will be established using protocols of the National Phenology Network. Students throughout the Y-K delta will record goose arrival times and key phenological events in grasses and woody plants. Second, students from Bethel Regional High School will be recruited to assist in the field research and be given the opportunity to develop small projects. Researchers will visit village classrooms each spring to introduce the project, climate change, and plant-animal interactions; share results of previous and ongoing research in the study area; and recruit interested students. Third, Native Alaskan undergraduate students through the Alaska Native Science and Engineering Program (ANSEP) will be recruited as field and laboratory technicians; these students may also develop their own projects. Fourth, Virtual Science will be used with local teachers to develop blogs, pod-casts, and instructional videos that can be distributed to remote classrooms throughout western Alaska and beyond. Fifth, objectives and results will be communicated to Native organizational bodies, which have representatives from each major village, to build knowledge and support for the research, and provide educational outlets for families who rely on geese for subsistence. Finally, one post-doctoral researcher, one graduate student, and several undergraduates will be provided new training, mentoring, and an opportunity to collaborate on project activities and present their findings at scientific meetings.