LTREB: Moose Population Cycles, Ecosystem Properties, and Landscape Patterns on Isle Royale

草食动物与生态系统相互作用的一般性理论难以建立，主要原因在于种群周期的长时间尺度、动植物种群相互作用的复杂空间尺度以及草食动物对植被与土壤之间碳和养分流动的非线性影响。这种理论上的困难由于缺乏长期的、景观尺度的研究而变得更加复杂。本研究将通过考察驼鹿（Alces Alces）的食用量空间分布与食用量、树径分布、针叶林基底面积和土壤氮有效性之间的关系，继续解决这些问题。一系列可供选择的假设将被验证：其中一个假设指出，空间格局不决定生态系统从先前的高驼鹿种群密度时期的恢复，而另一个假设提出了空间格局动态在生态系统恢复中的核心作用。每个生态系统属性的平均值的变化将通过检查网格点随时间的趋势来检验。这个长期的研究项目涵盖了一段时间，在这段时间里，该系统经历了最大和最小的驼鹿种群密度。这些极端的种群动态将为研究食草动物对大尺度植物群落动态和生态系统过程的影响提供有价值的信息。

9806313 Pastor The difficulties in developing a general theory of herbivore-ecosystem interactions arise from the long time-scales of population cycles, the complex spatial scaling of interactions between animal and plant populations, and thenon-linear effect of herbivores on carbon and nutrient flows between vegetation and soil. Such theoretical difficulties are compounded by the paucity of long-term, landscape-scale studies. This LTREB research will continue to address these problems by examining the spatial distribution of browse consumption by moose (Alces alces) in relation to browse supply, tree diameter distributions, conifer basal area, and soil nitrogen availability in the boreal forests of two valleys on Isle Royale. A series of alternative hypotheses will be tested: One series of hypotheses states that spatial patterns do not determine ecosystem recovery from the prior period of high moose population densities, while the alternative series of hypotheses invoke a central role of the dynamics of spatial patterns in ecosystem recovery. Changes in mean values of each ecosystem property will be tested by examining trends at grid points through time. This long-term research program covers a period of time in which the system has experienced the both the largest and smallest moose population densities. These extremes in population dynamics will provide valuable information on the effects of herbivores on large-scale plant community dynamics and ecosystem processes.