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

9806313牧师发展草食动物-生态系统相互作用的一般理论的困难来自于种群周期的长时间尺度、动植物种群之间相互作用的复杂空间尺度，以及草食动物对植被和土壤之间的碳和养分流动的非线性影响。由于缺乏长期的、横向的研究，这些理论上的困难变得更加复杂。LTREB的这项研究将继续解决这些问题，通过检查驼鹿(Alces Alce)与觅食供应、树木直径分布、针叶树断面积和土壤氮素有效性的关系的空间分布，在皇家岛两个山谷的北方森林中。将检验一系列替代假说：其中一系列假说表明，空间格局不决定生态系统从驼鹿种群密度较高的前期恢复，而另一系列假说调用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测试。这一长期研究计划涵盖了系统经历了最大和最小驼鹿种群密度的一段时间。种群动态的这些极端现象将提供关于食草动物对大规模植物群落动态和生态系统过程的影响的有价值的信息。

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.