Ecosystem and Population Consequences of Alien Grass Invasion of Seasonally Dry Hawaiian Woodlands

外来草类入侵是一种普遍现象 世界范围内，具有戏剧性社区的潜力， 生态系统的影响。 本研究将调查 外来草入侵引起的生态系统特性 氮有限，季节性干燥的林地在夏威夷和自然 热带稀树草原在委内瑞拉。 夏威夷的生态系统非常适合 测试，因为社区的相对简单， 可以方便地记录入侵。 两种草种 入侵这些林地的模式很明显 裂果蕨侵入未受干扰的林地， 火 火灾后，Melinis minutiflora在很大程度上取代了两者 Schizachyrium和本地林地物种导致低 多样性，更容易被烧毁的草原。 养分有效性 “火”的变化，“火”的变化。 植被变化可能与可预测的变化一致 土壤养分。 研究人员建议调查 驱动植被和土壤养分变化的过程， 研究火灾的影响和火灾后外星人的存在 草的营养限制。 具体来说，他们将测试 草入侵引起大规模变化的假设， 养分循环，这些变化反馈影响 涉及本地和引入的群体水平过程 物种 委内瑞拉的研究将允许测试的一般性 任何结论。

Invasions by introduced grasses are a common phenomenon worldwide, with the potential for dramatic community and ecosystem-level effects. This study will investigate changes in ecosystem properties induced by alien grass invasion in a nitrogen-limited, seasonally dry woodland in Hawai'i and a natural savanna lands in Venezuela. Hawaiian ecosystems are ideal for such tests because of the relative simplicity of the communities and the ease with which invasions can be documented. Two grass species have a distinct pattern of invasion into theses woodlands: Schizachyrium condensatum invades undisturbed woodland and promotes fire. After fire, Melinis minutiflora largely replaces both Schizachyrium and native woodland species resulting in a low diversity, more readily burned grassland. Nutrient availability changes predictably with fire, yielding, a clear pattern of vegetation change that likely coincides with a predictable change in soil nutrients. The researchers propose to investigate the processes driving vegetation and soil nutrient changes and to examine the influence of fire and the post-fire presence of alien grasses on nutrient limitation. Specifically, they will test the hypothesis that grass invasion induces largescale changes in nutrient cycling and that these changes feedback to influence population-level processes involving both native and introduced species. The Venezuela study will permit tests of the generality of any conclusions.