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

[摘要]本项目由阿拉斯加大学和科罗拉多州立大学合作开展。该项目由极地项目办公室、环境生物学和生态学部门以及生态系统研究部门资助。在接下来的五年里，主要研究人员将研究阿拉斯加育空-库斯科维姆三角洲沿海苔原鹅放牧系统中植物-草食相互作用和相关生态系统过程的时空变化。他们的基本假设是草食动物和早期演替状态之间的相互作用是紧密耦合的，因此草食动物需要这些早期演替状态来成功地生产后代。此外，食草动物不仅维持，而且能够通过放牧相关活动创造这些早期演替状态。此外，植被格局的时空复杂性和草食动物对生境斑块的响应给演替、生态系统过程和草食动物种群动态带来了实质性的复杂性。主要研究者将研究四个相互关联的假设：1)草食对演替的影响；2)草食对养分循环过程的影响；3)植被对草食的演替响应存在时间滞后；4)草食时空格局对生态系统状态的影响。这一建议是基于对在Y-K三角洲沿岸筑巢的黑雁（Branta bernicla nigricans）的营养和其他因素的16年研究，以及对植被/生态系统对草食反应的7年研究。这项研究利用了大量单独标记的植物样本，这将为研究小组提供一个前所未有的机会来衡量食草动物对食物质量和数量的人口反应。密集的草食对土壤过程影响的复杂实验。首席研究人员将使用空间生态系统模型（SAVANNA）的修改版本来测试假设，否则无法检查草食空间模式与生态系统状态之间的关系。SAVANNA将直接与鹅种群模型联系起来，以充分将草食动物动态纳入他们的假设检验中，并且现场实验旨在使他们能够将SAVANNA参数化为沿海冻土带。建模也将有助于指导他们的实地实验和监测跨营养水平的充分整合。目前的项目还将把对墨西哥同一群鹅和相关湿地栖息地的研究联系起来。这可能是首次在如此广阔的空间尺度上全面整合生态系统背景下土壤过程、植被和草食动态的研究。

AbstractOPP-99-85831SedingerThis 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.