Using restoration to test community assembly in a heavily invaded ecosystem

生态恢复是协助生态系统恢复的过程，是减轻自然系统人为退化影响的重要工具。例如，旱地的恢复已被用于防治荒漠化，溪流的恢复可以改善鲑鱼等鱼类的栖息地。然而，尽管它很重要，恢复项目的成功可能很难实现，而且结果往往是不可预测的。鉴于这些挑战，我的研究项目寻求将生态理论与恢复实践联系起来，以提高恢复的可预测性和成功性。在接下来的五年里，我将运用群落聚集理论和基于性状的生态学来揭示生态对干扰、入侵和恢复的反应机制。群落组合框架侧重于环境如何过滤掉不太适应当地条件的物种。特别强的过滤器将选择植物性状的子集，例如干燥条件过滤掉用水效率低的物种。这可能导致群落内的趋同，所有物种都有一组相似的特征来响应最强的过滤器。我将通过结合大型和小规模的实地实验和观察研究来评估干扰在草本群落中作为过滤器的作用。具体来说，我的研究集中在不列颠哥伦比亚省的加里橡树草地上。基于低强度鹿压力到高强度鹿压力的梯度，我将跟踪群落特征随着放牧强度的增加而趋同。干扰也与非本地物种入侵率的增加有关，尽管这通常被理解为外来物种的到来和殖民化，而不是外来物种固有的特征。然而，外来物种可能基于它们与人类的关系，代表了一组强烈偏见的生殖和生长性状，可能在种子投入中得到更好的代表，并且可能逃脱放牧等干扰。因此，外来物种对放牧的反应可能与本地物种不同，并且如果忽略来源，可能以不可预测的方式驱动群落在干扰前、期间和之后的聚集。因此，我的工作将同时考虑社区集会中的干扰和入侵，它们既是退化社区组成的驱动因素，也是恢复行动下恢复的预测因素。我将分别评估放牧对本地物种和外来物种性状的影响，并将通过跟踪鹿的饮食偏好、草地上的种子投入和外来物种性状的偏见来分析为什么外来物种可能会有不同的反应。最后，我将测试管理放牧，去除外来物种，或实施这两种策略如何影响土著社区的恢复结果。我的工作将为加拿大最优先的保护区之一的管理提供信息，并将加强对干扰和入侵如何改变社区聚集模式的生态学理解。

Ecological restoration, the process of assisting the recovery of an ecosystem, is an essential tool for mitigating the effects of human-induced degradation in natural systems. For example, restoration in drylands has been used to fight desertification, and stream restoration can enhance habitat for fish such as salmon. Despite its importance, however, success in restoration projects can be difficult to achieve, and outcomes are often unpredictable. In light of these challenges, my research program seeks to link ecological theory and restoration practice to enhance the predictability and success of restoration. Over the next five years, I will use theories of community assembly and trait-based ecology to uncover mechanisms of ecological responses to disturbance, invasion, and restoration. Community assembly frameworks focus on how the environment acts to filter out species that are not well adapted to local conditions. Particularly strong filters will select for a subset of plant traits, such as dry conditions filtering out species that use water inefficiently. This can cause convergence within a community, with all species having a similar set of traits in response to the strongest filter. I will assess the role of disturbance as a filter in herbaceous communities through a combination of large- and small-scale field experiments and observational studies. Specifically, my research focuses on Garry oak meadows in British Columbia. Based on a gradient of low intensity deer pressure to high intensity, I will track community trait convergence as grazing intensifies. Disturbance is also linked to increased rates of invasion by non-native species, though this is generally understood in terms of arrival and colonization rather than traits intrinsic to exotic species. However, exotic species may represent a strongly biased set of reproductive and growth traits based on their relationship to humans, may be better represented in seed inputs, and may escape disturbances like grazing. Thus, exotic species' response to grazing may be distinct from natives, and may drive community assembly pre-, during, and post-disturbance in unpredictable ways if origin is ignored. As a result, my work will simultaneously consider disturbance and invasion in community assembly, both as drivers of composition in degraded communities and as predictors of recovery under restoration actions. I will assess grazing impacts on traits in native and exotic species separately and together, and will pull apart why exotic species may respond differently by tracking deer diet preferences, seed inputs in meadows, and bias in exotic species traits. Finally, I will test how managing grazing, removing exotics, or implementing both strategies influence restoration outcomes in native communities. My work will inform management in one of the highest priority conservation areas of Canada, and will enhance ecological understanding of how disturbance and invasion alter community assembly patterns.