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

季节性干旱的夏威夷林地外来草入侵的生态系统和人口后果

基本信息

批准号：
9119618
负责人：
Carla D'Antonio
金额：
$ 59.13万
依托单位：
University of California-Berkeley
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
1992
资助国家：
美国
起止时间：
1992-06-01 至 1998-05-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=9119618&HistoricalAwards=false
关键词：
Ecosystem Population Consequences Alien Grass

项目摘要

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.

外来草类的入侵是世界范围内的普遍现象，可能对社区和生态系统产生巨大影响。这项研究将调查夏威夷氮限制性季节性干燥林地和委内瑞拉天然稀树草原上因外来草入侵而引起的生态系统特性的变化。夏威夷生态系统非常适合进行此类测试，因为这里的群落相对简单，而且很容易记录入侵行为。两种草类入侵这些林地的方式不同：Schizachyrium condensatum 入侵未受干扰的林地并助长火灾。火灾发生后，小花草在很大程度上取代了裂殖属和本地林地物种，导致草原多样性较低，更容易被烧毁。养分可用性随火灾、产量而发生可预测的变化，植被变化的明显模式可能与土壤养分的可预测变化相一致。研究人员提议调查驱动植被和土壤养分变化的过程，并研究火灾和火灾后外来草的存在对养分限制的影响。具体来说，他们将检验以下假设：草类入侵会引起养分循环的大规模变化，并且这些变化会反馈影响涉及本地和引进物种的种群水平过程。委内瑞拉的研究将允许检验任何结论的普遍性。