Linking Forest Regeneration, Plant Distributions, and Ecotone Dynamics in Changing Mountain Environments

该研究项目将研究树种的分布以及落叶和针叶生态系统之间的边界如何在多个空间尺度上响应不断变化的环境条件。该项目将通过检验理论生态学、气候梯度生物地理学和入侵生态学的概念，扩展目前关于树苗在新地区定居或在其他地区招募不足的机制的知识。利用预测模型，该项目将为适应森林气候条件变化的策略提供新的见解，这些森林为美国东北部提供了宝贵的生态和社会经济服务。研究结果将通过在区域自然游客中心、专业协会和公共利益团体会议以及一个公众访问网站的介绍或展览向区域森林管理机构和公众传播。该项目还将通过研究生培训和扩大本科生参与研究，为改善科学、技术、工程和数学（STEM）领域的教育做出贡献。山区在气候和相关生物群落方面具有空间压缩的海拔梯度。因此，它们很容易受到环境变化的影响。山地过渡带，如低海拔落叶林和高海拔针叶林之间的过渡，特别有利于探测物种分布的变化。近几十年来，由于气温升高和生长季节延长，全球许多高海拔树线都出现了上坡。研究人员将量化正在进行的树种人口变化，以提供美国东北部海拔气候梯度未来潜在变化的早期指标。他们还将分析林下植被的多样性和组成是如何沿着海拔气候梯度变化的，他们将确定林下植被的组成和多样性是如何影响不同物种的树苗建立和补充沿空间环境梯度。本文将对封闭林冠和林隙条件下林下植物群落组成、光环境、小气候和树苗库进行特征分析。树种在海拔上的大小级分布将使用logistic模型进行分析。利用广义线性模型（GLM）和非度量多维尺度对林下植物多样性和组成梯度进行表征，并建立各主要树种相对于环境梯度和林下植被的树木更新模型。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。

This research project will investigate how distributions of tree species and boundaries between deciduous and coniferous ecosystems respond to changing environmental conditions across multiple spatial scales The project will expand current knowledge about the mechanisms through which tree seedlings colonize new areas or experience poor recruitment in other areas by testing hypotheses that integrate concepts from theoretical ecology, biogeography of climatic gradients, and invasion ecology. Using predictive modeling, the project will provide new insights about strategies for adapting to changing climatic conditions in forests that provide valuable ecological and socioeconomic services in the northeastern United States. Research findings will be disseminated to regional forest management agencies and the general public via presentations or exhibits in regional nature visitor centers, meetings of professional societies and public interest groups, and a public-access website. The project also will contribute to improved education in science, technology, engineering, and mathematics (STEM) fields through graduate training and expansion of undergraduate participation in research.Mountain regions contain spatially compressed elevational gradients in climate and associated biological communities. As a result, they are vulnerable to environmental changes. Montane ecotones, such as the transition between low-elevation deciduous and high-elevation coniferous forests, are particularly conducive to detecting changes in species distributions. Many high-elevation treelines across the globe have advanced upslope in recent decades in direct response to increasing temperature and growing season length. The investigators will quantify ongoing demographic shifts in tree species to provide an early indicator of potential future changes along elevational climatic gradients of northeastern United States. They will also analyze how the diversity and composition of forest understories change along elevational climatic gradients, and they will determine how forest understory composition and diversity affect the establishment and recruitment of tree seedlings of various species along spatial environmental gradients. Understory plant community composition, light environment, microclimate, and tree seedling banks will be characterized and analyzed in closed canopy settings and in forest gaps. Size-class distributions of tree species over elevation will be analyzed using logistic models. Understory plant diversity and compositional gradients will be characterized with generalized linear models (GLM) and non-metric multidimensional scaling, and GLM-based tree regeneration models will be developed for each major tree species relative to the environmental gradients and understory vegetation.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.