DISSERTATION RESEARCH: Testing the limits: effects of climate and competition on conifer distributions at Mount Rainier

气候变化将如何影响我们的森林？气温上升可能导致物种分布的变化。事实上，科学家们已经观察到，在过去的世纪里，随着全球气温的上升，许多物种的分布范围在纬度和海拔上都有所上升。然而，与邻近树木的竞争也会影响物种的分布，结果是范围的变化可能比仅基于温度的直接影响所预期的更难以预测。本项目将通过研究气候（包括温度、雨和雪）如何与竞争相互作用来确定雷尼尔山国家公园三种常见树种的表现，从而解决这些问题。对过去100年来树木生长和气候数据的研究表明，气候决定了许多树种的范围上限，但其他因素对范围下限也很重要。这些模式将通过移植超出其目前范围限制的物种的种子和幼苗以及从某些地区清除竞争对手来进行测试。结合观测数据，这些实验将被用来检验这样的假设，即生物因素，如竞争，在下限范围内更重要，而非生物因素，如温度，控制上限范围。预测气候变化对树木的影响是自然资源规划者和土地管理者的一个巨大挑战，他们的管理计划依赖于了解物种现在在哪里以及未来几十年将在哪里出现。这项研究直接适用于国家公园管理局，特别是雷尼尔山国家公园。公园内的古老森林目前提供了重要的生态系统服务，包括碳固存和稀有物种的栖息地，这些研究将提供有关这些重要生态系统未来可能如何变化的信息。

How will climate change affect our forests? Rising temperatures could result in changes in the distribution of species. Indeed, scientists have already observed that many species ranges have moved upward in latitude and altitude as global temperatures have increased during the past century. However, competition with neighboring trees can also affect the distribution of species, with the result that range changes may be more difficult to predict than would be expected based only on the direct effects of temperature. This project will address these issues by examining how climate (including temperature, rain, and snow) interacts with competition to determine the performance of three common tree species at Mount Rainier National Park. Examination of yearly tree growth and climate data that span the last 100 years indicates that climate determines upper range limits for many tree species, but that other factors are important at lower range limits. These patterns will be tested by transplanting seeds and seedlings of species beyond their current range limits and by removing competitors from some areas. In combination with observational data, these experiments will be used to test the hypothesis that biotic factors, such as competition, are more important at the lower range limit, while abiotic factors, such as temperature, control the upper range limit.Predicting the impacts of climate change on trees is a great challenge for natural resource planners and land managers, whose management plans rely on knowing where species occur now and where they will occur in future decades. This research is directly applicable to the National Park Service, especially at Mount Rainier National Park. Old growth forests in the Park currently offer significant ecosystem services, including carbon sequestration and habitat for rare species, and these studies will provide information about how these important ecosystems may change in the future.