Ecosystems in Transition: Causes and Cosequences of Dramatic Shifts in Growth Form Dominance

转型中的生态系统：生长形态急剧转变的原因和后果在世界范围内，由于气候手段和极端气候的全球变化、大气中二氧化碳、氮沉积的增加、土地管理的变化以及外来入侵物种的传播，许多生态系统的结构和功能都在转型中。在大平原东部的高草草原上，灌木覆盖率扩大，森林侵占这片草原是一个普遍现象。这是一个严重的保护问题，因为Tallgras草原被认为是濒危的生态系统。该项目的目标是利用高草草原生态系统来评估过渡到郁闭式灌木/林地的模式、机制和生态后果。我们将检验关于资源可获得性在草原木本植物扩展中所起作用的假设。在从树叶到景观的层面上评估这种草原到灌木丛的转变，将提供成功保护努力所需的机械特性和大规模普遍性。

Abstract00-75350BriggsEcosystems in transition: Causes and consequences of dramatic shifts in growth form dominanceWorldwide, the structure and function of many ecosystems are in transition due to global changes in climatic means and extremes, increased atmospheric CO2, nitrogen deposition, alterations in land management, and the spread of invasive exotic species. In the tallgrass prairies of the eastern Great Plains, the expansion of shrub cover and forest encroachment into this grassland is a widespread phenomenon. This is a serious conservation concern since tallgrass prairie is considered an endangered ecosystem. The objective of this project is to use a tallgrass prairie ecosystem to evaluate the patterns, mechanisms and ecological consequences of transition to closed-canopy shrub/woodland. We will test hypotheses regarding the role that resource availability plays in woody plant expansion in grasslands. Evaluating this grassland-to-shrubland transition at levels from the leaf to the landscape will provide both the mechanistic specificity, as well as the large-scale generality, required for successful conservation efforts.