Dissertation Research: Mechanisms of Species Compositional Change Due to Gap Creation in a Tallgrass Prairie

论文研究：高草草原间隙造成的物种组成变化机制

• 批准号: 9701250
• 负责人: Deborah Goldberg
• 金额: $ 0.57万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-05-01 至 1999-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9701250&HistoricalAwards=false
• 关键词: Dissertation; Research; Mechanisms; Species; Compositional

9701250 Goldberg In this proposal, the PIs develop a framework to determine the mechanisms of species compositional change following the creation of a gap. It is critical that we learn the mechanistic basis for these changes to understand the process of, and thereby develop models for, gap dynamics. Release from competition due to reduction of neighbor biomass has been the assumed, but largely untested, mechanism responsible for species compositional change in disturbances. The competitive release hypothesis predicts that the competitive hierarchy remains unchanged but competitive inferior species are able to colonize a gap faster than the dominants. However, the PIs suggest that the competitive hierarchy may also shift in favor of species adapted to disturbed conditions. At least two other mechanisms of change could cause this shift in hierarchy: alterations in the abiotic environment independent of biotic effects and changes in neighborhood size-structure. The PIs will separate these three potential mechanisms of change in factorial manipulations of neighbor biomass (removed or present), abiotic soil alteration (soil disturbed or undisturbed) and neighborhood size-structure (juvenile colonists or adults). Data on the absolute and relative performance due to each of these components will allow us to compare the responses of six target species. Preliminary results suggest that the experimental design is able to separate these effects and that species characteristic of gaps respond differently to components of change compared to non-gap species.

9701250 Goldberg 在本提案中，PI 开发了一个框架来确定间隙产生后物种组成变化的机制。至关重要的是，我们必须了解这些变化的机制基础，以了解差距动态的过程，从而开发差距动态模型。由于邻近生物量的减少而从竞争中释放出来已经被认为是导致干扰中物种组成变化的机制，但在很大程度上未经测试。竞争性释放假说预测，竞争等级保持不变，但竞争性劣等物种能够比优势物种更快地占据间隙。然而，PI表明，竞争等级也可能转向有利于适应干扰条件的物种。至少还有另外两种变化机制可能导致这种层次结构的转变：独立于生物效应的非生物环境的改变和邻里规模结构的变化。 PI 将区分邻近生物量（已移除或存在）、非生物土壤改变（土壤扰动或未扰动）和邻近规模结构（幼年殖民者或成人）的因子操作中的这三种潜在变化机制。有关每个组件的绝对和相对性能的数据将使我们能够比较六个目标物种的响应。初步结果表明，实验设计能够区分这些影响，并且与非间隙物种相比，间隙物种特征对变化组成部分的反应不同。