Doctoral Dissertation Research: Assessing geographic patterns of negative density dependence in temperate tree species.

森林群落的发展是由环境因素和生物体之间的相互作用形成的。 热带和温带森林的最新证据表明，寄主特异性病原体在形成幼苗阶段的森林群落发展中发挥着重要作用，特别是对于数量较少的物种。从幼苗到幼树的过渡是树木生命周期的一个关键阶段，它将决定未来几年森林群落的组成。 该项目的目标是，利用在天然林和温室中的实验，确定病原体在决定幼苗向幼树过渡的结果方面的作用，这与植物与同一物种的成年树木的接近程度有关。将在三个不同的森林中对幼苗和树苗进行取样，所有直径大于1厘米的树木都已绘制地图并贴上标签。 这些位于弗吉尼亚州、印第安纳州和威斯康星州的森林将为东温带森林提供广泛的地理样本。将对几个物种的幼苗和树苗的存活和生长情况进行为期两年的跟踪，以确定它们在随机选择的成年树木周围的死亡率和生长率。 研究结果将为温室研究的物种选择提供信息，以确定森林中幼苗成功或失败背后的因素。 研究人员预测，群落中的稀有物种在生命早期阶段比常见物种更容易受到病原体的影响。森林对人类社会的可持续发展至关重要，并提供了必不可少的可再生资源。 因此，必须了解森林是如何生长和发展的。 这项研究将通过强调病原体驱动的死亡率在构建森林群落中的作用，为森林系统的保护和管理工作提供信息。此外，它将提供证据，说明森林再生如何可能受到气候变化的影响，通过检查物种性能的区域差异跨越纬度梯度。 最后，研究人员将继续与地方和国家土地保护机构建立外联伙伴关系，教育公众了解这项研究的结果和森林的重要性。

The development of forest communities is shaped by both environmental factors and interactions between organisms. Recent evidence from both tropical and temperate forests suggests that host-specific pathogens play a major role in shaping forest community development at seedling stage, especially for less abundant species. The seedling to sapling transition is a critical stage of the tree life cycle that will determine forest community composition for years to come. The goal of this project is to determine, using experiments in natural forests and the greenhouse, the role of pathogens in determining the outcome of the seedling to sapling transition in relation to the plants' proximity to adult trees of the same species. Seedlings and saplings will be sampled in three different forests where all trees greater than 1 centimeter diameter have been mapped and tagged. These forests in Virginia, Indiana and Wisconsin will provide a broad geographic sampling of eastern temperate forests. The survival and growth of seedlings and saplings of several species will be tracked for two years to determine their rates of mortality and growth around randomly selected adult trees. The results will inform species selection for greenhouse studies to determine the factors behind seedling success or failure in the forests. The researchers predict that rare species in the community will be more affected by pathogens in the early life stages than more common species.Forests are vital to a sustainable human society and provide an essential renewable resource. It is therefore important to understand how forests grow and develop. This research will inform conservation and management efforts of forest systems by highlighting the role that pathogen-driven mortality has in structuring forest communities. Additionally, it will provide evidence on how forest regeneration may be affected by climate change by examining the regional differences in species performance across a latitudinal gradient. Finally, the researchers will continue their outreach partnerships with local and national land conservancies to educate the public on the results of this research and the importance of forest in general.