Topography and forest dynamics

气候、土壤类型和地形对植物物种、群落和植被类型分布的影响是生态学长期关注的话题。在不断变化的环境条件及其对保护优先事项的影响的背景下，这些主题具有新的紧迫性。在一个地区发现的植物和森林的类型在很大程度上取决于该地区的降雨量、平均温度和相关的土壤。随着一个地区气候的变化，组成森林的植物也会发生变化，因为它变得更适合某些物种生存，而不再适合其他物种的生存。该项目利用北加州沿海地区一个经过充分研究的山地系统来研究气候变化、极端气候事件以及降雨和温度的变化如何影响当前和未来的森林结构。这项工作的目标是确定哪些类型的植物群落在组成其成员的物种中会经历更迅速的变化，以及哪些森林可能对变化最有弹性。这项工作将通过与当地自然保护区以及与资源管理和养护机构的合作，促进森林的养护。该项目将培训社区大学的学生学习林业课程，并将促进他们转入四年制大学。本项目利用沿海山地系统沿线的良好调查地点、高分辨率气候和植被层以及跨大地理范围的物种建模方法，研究了年际气候变率、极端事件、温度和降雨模式变化对当前和未来植物分布模式的作用。沿着南北朝向海拔梯度的地点的使用提供了一个机会来检查这些变化的环境条件对降雨和温度变化的森林的相对影响。这项工作将测试以下三个假设来解释物种更替和变化的分布模式：1)局部避难所假说，假设凉爽/潮湿的地点将缓冲群落免受气候条件变化的影响；2)尾缘/前沿假说，预测凉爽/潮湿的地点的影响将更大，因为这些地方将被接近其气候耐受性边缘的物种所占据；3)非对称传播体有效性假说，该假说预测与热/干和冷/湿地区相关的扩散策略将促进或限制一个地区的变化速度。这项工作解决了森林群落中单个物种动态与群落变化之间的关键联系，并将为研究人员和土地管理者如何理解生态系统对快速环境变化的动态反应提供信息。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The influences of climate, soil types and topography on the distributions of plant species, communities and vegetation types are topics of long-standing interest in ecology. These topics have taken on renewed urgency in the context of changing environmental conditions and their impacts on conservation priorities. The type of plants and forests found in an area is largely determined by the amount of rainfall the area receives, its average temperature and its associated soils. As the climate of an area changes, it is expected that the plants that make up a forest will change as it becomes more hospitable for some species and is no longer appropriate for the survival of others. This project uses a well-studied mountain system in coastal Northern California to examine how climate variability, extreme climate events, and changes in rainfall and temperature may influence the current and future structure of forests. The goal of this work is to determine which types of plant communities will undergo a more rapid change in the species that make up its members and which forests may be most resilient to change. This work will contribute to the conservation of forests through its work with a local nature preserve, as well as with resource management and conservation agencies. This project will train community college students in a forestry program and will facilitate their transfer to four-year Universities. Using well surveyed sites along a coastal mountain system, high resolution climate and vegetation layers, and species modeling approaches across large geographic ranges, this project examines the role that inter-annual climate variability, extreme events, and changing temperature and rainfall patterns have on current and future plant distribution patterns. The use of sites along north and south facing elevation gradients provides an opportunity to examine the relative effect of these changing environmental conditions on forests that vary in rainfall and temperature. This work will test the following three hypotheses to explain species turnover and changing distribution patterns: 1) the local refugia hypothesis which posits that cool/moist locations will buffer communities from changing climatic conditions, 2) the trailing/leading edge hypothesis which predicts that impacts will be greater in cool/moist locations, as these will be occupied by species that are approaching the edges of their climatic tolerances, and 3) the asymmetric propagule availability hypothesis which predicts that dispersal strategies associated with hot/dry and cool/moist areas will facilitate or limit the rate of change found in an area. This work addresses the critical linkages between individual species dynamics and community change in forest communities and will the inform how researchers and land managers understand the dynamic responses of ecosystems to rapid environmental change.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.