Doctoral Dissertation Research: Factors Affecting Forest Development and Stand Dynamics in Oak Forests in the Eastern U.S.

这项博士论文研究项目将研究美国东部落叶林中观察到的栎属物种更新率下降的原因。该项目将使用多种基于实地和分析的方法，调查可能导致橡树更新率下降的多种因素，包括干扰制度修改、气候变化、土地利用历史遗留问题和非生物环境条件。项目成果将为了解美国东部橡树林中发生的复杂动态提供亟需的见解，并将增加有关土地利用遗留问题和多种相互作用的森林驱动因素(如树冠干扰和干旱事件)对生态系统影响的理论知识。由于橡树林为野生动物提供食物和栖息地，支持相关的植物群落，提供宝贵的木材，并提供风景优美的娱乐机会，从而为社会提供重要的生态、经济和社会效益，该项目将通过提供关于缩小以橡树为主的森林范围的机制的信息和见解，帮助保护这些好处。该项目还应提出可能的森林管理计划，以防止这种重要物种的丧失。该项目将为本科生提供特殊教育和培训机会，帮助他们收集实地数据和进行实验室分析。这一项目的成果将通过学术出版物和专题介绍以及研究区土地管理办公室的教育外联活动广泛传播。作为博士论文研究改进奖，该奖项还将提供支持，使有前途的学生能够建立强大的独立研究事业。过去5000年来，橡树林一直是东部落叶林的主导，其生态、商业和社会重要性代表着整个美国东部独特的长期遗产，但整个地区的橡树物种无法再生，因为越来越多的林下耐荫物种阻止光线到达森林地面上的橡树幼苗和树苗。该项目的目标是阐明多种森林驱动因素的相对重要性和特定地点的性质，并查明不同驱动因素之间的相互作用。这位博士生将使用森林调查、树木年代学和土地调查分析方法来调查威斯康星州西南部漂流地区这种成分转移的多个驱动因素，该地区的橡树更新显著减少。她将研究19世纪40年代和40年代的土地调查以及现代森林调查数据，以确定整个研究地区发生的森林发展轨迹。她将使用树枝生态学方法记录树冠干扰历史，并量化气候和放射状树木生长之间的关系。她将使用结构方程模型来分析土地利用遗产、树冠干扰历史、气候和特定地点的非生物因素对橡树更新的相对影响。

This doctoral dissertation research project will examine the factors contributing to the observed decline in oak (Quercus) species regeneration across the deciduous forests of the eastern United States. Using a variety of field-based and analytical methods, this project will investigate the multiple factors that may be contributing to decline rates in oak regeneration, including disturbance regime modifications, climatic change, land-use history legacies, and abiotic environmental conditions. Project results will provide much-needed insights into the complex dynamics occurring in oak forests across the eastern U.S., and they will increase theoretical knowledge regarding the ecosystem effects of land-use legacies and multiple, interacting forest drivers, such as canopy disturbances and drought events. Because oak forests offer important ecological, economic, and social benefits to society by producing food and habitat for wildlife, supporting associated vegetative communities, providing valuable timber, and offering scenic opportunities for recreation, this project will assist in the conservation of these benefits by providing information and insights regarding the mechanisms that are reducing the range of oak-dominated forests. The project also should suggest possible forest-management plans to prevent the loss of this important genus. The project will offer special education and training opportunities for undergraduate students who will assist with both field data collection and laboratory analysis. Results from this project will be disseminated broadly through scholarly publications and presentations and through educational outreach activities at land-management offices in the study area. As a Doctoral Dissertation Research Improvement award, this award also will provide support to enable a promising student to establish a strong independent research career.Having dominated eastern deciduous forests for the past 5,000 years, the ecological, commercial, and societal importance of oak forests represents a distinctive long-term legacy across the eastern U.S., but oak species throughout the region are failing to regenerate due to the increased abundance of understory shade-tolerant species that prohibit light from reaching oak seedlings and saplings on the forest floor. The goal of this project is to elucidate the relative importance and the site-specific nature of the multiple forest drivers and to identify interactions among different drivers. The doctoral student will use forest-inventory, dendrochronological, and land-survey analysis methods to investigate multiple drivers of this compositional shift across the Driftless Area in southwestern Wisconsin, an area undergoing significant decreases in oak regeneration. She will examine land surveys from the 1840s and 1940s alongside modern forest inventory data to identify the forest development trajectories occurring throughout the study area. She will employ dendroecological methods to document canopy disturbance histories and to quantify the relationship between climate and radial tree growth. She will use structural equation modeling to analyze the relative influence of land-use legacies, canopy-disturbance history, climate, and site-specific abiotic factors on oak regeneration.