The influence of plant functional traits on ecosystem responses to altered rainfall

在未来几十年，生态群落将经历许多环境变化，包括气候变化和外来物种的入侵。当物种遇到限制其生长和繁殖的生理阈值时，植物和微生物群落可能对这些环境变化表现出非线性反应。最终，生态系统对环境变化的响应既取决于物种生理或生长的短期变化，也取决于物种组成的长期变化。该项目将有助于了解生态系统对环境变化的反应，这将是长期可持续管理灌木林生态系统所必需的。实验、观测和建模方法将用于量化灌木林生态系统对降雨变化的响应。利用雨棚产生降雨量梯度，并通过去除入侵的一年生草来控制试验田的初始物种组成。将对焦点物种进行短期生理测量，并在实验过程中对其进行监测，以测量其生长和存活情况。为了补充这些实验，将对南加州沿自然降雨梯度的优势植物物种进行类似的测量。这些实验和调查的结果将用于参数化动态全球植被模型，以预测降雨制度的预测变化将如何影响植物物种组成，并最终影响区域生态系统过程。这个项目将有助于本科生、研究生和公共教育，它将向更广泛的科学界提供数据，并将通知土地管理机构。该实验将为本科生和研究生提供研究机会。此外，研究将评估入侵如何影响生态系统对全球变化的响应，以及降雨量的年际变化是否可能为本土灌木恢复创造机会。将这些发现与有关的保护和土地管理组织交流将是这项试验最重要的成果之一。最后，该项目将提供所有可用的数据，并通过在公共场所的夜间讲座来支持关于全球变化的生态影响的交流。

In the coming decades, ecological communities will experience numerous environmental changes, including shifting climates and invasion by exotic species. Plant and microbial communities may exhibit non-linear responses to these environmental changes as species encounter physiological thresholds that constrain their growth and reproduction. Ultimately, ecosystem responses to environmental change will depend both on short-term shifts in species physiology or growth, and long-term shifts in species composition. This project will help develop the understanding of ecosystem responses to environmental change that will be needed for sustainable long term management of chaparral ecosystems.Experimental, observational, and modeling approaches will be used to quantify chaparral ecosystem responses to altered rainfall regimes. Rainout shelters will be used to produce a gradient of rainfall quantity, and initial species composition of the experimental plots will be controlled by removing invasive annual grasses. Short-term physiological measurements will be taken on focal species, which will also be monitored over the course of the experiment to measure growth and survival. To complement these experiments, similar measurements will be taken on dominant plant species along a natural rainfall gradient across Southern California. Results from these experiments and surveys will be used to parameterize a Dynamic Global Vegetation Model to predict how predicted shifts in rainfall regimes will influence plant species composition and, ultimately, influence regional ecosystem processes.This project will contribute to undergraduate, graduate, and public education, it will provide data to the broader scientific community, and it will inform land-management agencies. The experiment will provide research opportunities both for undergraduate and graduate students. Further, the research will evaluate how invasion influences ecosystem responses to global change, and whether interannual variation in rainfall may create opportunities for native shrub restoration. Communicating these findings with relevant conservation and land-management organizations will be one of the most important outcomes from this experiment. Finally, the project will make all of the data available and support communication about the ecological impacts of global change through evening lectures in public venues.