Plant community assembly and disassembly with climate change

气候对生态群落组成的影响有多大？如果气候是构建群落的主要力量，气候变暖应该可以预见地导致冷适应物种的丧失，代价是当地社区适应温暖的物种。或者，如果区域气候没有很强地构建当地社区，那么物种组成可能不会随着气候变化而发生太大变化。然而，经历气候变暖的当地社区的物种构成明显缺乏变化，也可能是由于物种改变其地理范围的能力有限，例如扩散速度缓慢。不幸的是，这两种可能性有着截然不同的影响；前者表明社区对气候变化可能有一定的适应能力，而后者意味着社区的敏感性，特别是在气候变化加速的情况下。这项研究将通过检验在两个太平洋西北国家公园收集的跨区域气候梯度的植物物种组成的独特历史数据集，来测试群落弹性与对最近和未来气候变化的敏感性的重要性。该项目将有助于我们了解气候变化的后果，并将这一信息传达给国家公园管理局和太平洋西北地区的其他资源管理人员。该项目还将为学生研究和培训提供机会，以加强科学工作能力。该项目将在预测气候变化的植物群落变化问题上取得进展，尽管存在区分具有相似预期结果的驱动因素的内在挑战。具体地说，该项目将确定气候对太平洋西北部山区植物群落的强烈影响。将使用30多年前在两个国家公园(北喀斯喀兹国家公园和雷尼尔山国家公园)收集的植物群落组成的重新调查数据集来检验关于群落组成和生物气候变量关系的假设。这些历史数据将与新开发的物种分布联合模型和影响小气候的景观特征的高分辨率数据相结合。研究目标是：1.评估宏观和小气候变量对群落组成的重要性；2.研究群落在过去40年中的变化，以确定最近气候变化的组成周转是否与气候缓冲(恢复力)与滞后物种反应(敏感性)一致；以及3.在群落组装的早期阶段，进行跨越大尺度和精细气候梯度的多物种种子添加实验，以分析补充限制和人口惯性(导致时滞敏感性的因素)和宏观或小气候缓冲(促进对气候变化的适应能力的因素)的作用。

How strongly does climate influence the composition of ecological communities? If climate is the predominant force structuring communities, climate warming should predictably result in the loss of cold-adapted species at the expense of warm-adapted species in local communities. Alternatively, if regional climate doesn't strongly structure local communities, then species composition may not change much with climate change. However, an apparent lack of change in the species composition of local communities experiencing climate warming can also arise from a limited ability of species to shift their geographic ranges, e.g., slow rate of dispersal. Unfortunately, these two possibilities have very different implications; the first suggests communities may be somewhat resilient to climate change, while the latter implies community sensitivity, especially as climate change accelerates. This research will test the importance of community resilience vs. sensitivity to recent and future climate change, by examining unique historic data sets of plant species composition collected across regional climatic gradients in two Pacific Northwest National Parks. The project will contribute to our understanding of the consequences of climate change and communicate this information to National Park Service and other resource managers in the Pacific Northwest. This project will also provide opportunities for student research and training that will strengthen the scientific workforce.This project will make progress on the problem of predicting change in plant communities with climate change given apparent stasis, despite the inherent challenges of differentiating drivers with similar expected outcomes. Specifically, this project will determine how strongly climate influences plant communities in the mountains of the Pacific Northwest. Hypotheses on relations of community composition and bioclimatic variables will be tested using resurvey data sets of plant community composition originally collected over 30 years ago in two National Parks (North Cascades National Park and Mount Rainier National Park). This historic data will be combined with newly developed joint species distribution models and high resolution data on the landscape features that influence microclimate. Research objectives are to: I. Assess the importance of macro and microclimatic variables for community composition; II. Examine community shifts over the last four decades to determine whether compositional turnover with recent climate change is consistent with climatic buffering (resilience) vs. lagged species responses (sensitivity); and III. Conduct a multi-species seed addition experiment across large-scale and fine-scale climatic gradients to parse out the roles of recruitment limitation and demographic inertia (factors that contributed to time-lagged sensitivity) and macro- or microclimatic buffering (factors that promote resilience to climate change) in the early stages of community assembly.