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

森林群落的发展既受环境因素的影响，也受生物间相互作用的影响。来自热带和温带森林的最新证据表明，寄主特有的病原体在苗期对森林群落的发育起着重要作用，特别是对于数量较少的物种。从苗木到幼树的过渡是树木生命周期的关键阶段，这将决定未来几年森林群落的组成。该项目的目标是通过在天然林和温室中的实验，确定病原体在决定苗木向树苗过渡的结果中所起的作用，这与植物与相同物种的成年树木的接近程度有关。苗木和树苗将在三个不同的森林中取样，所有直径超过1厘米的树木都已被绘制和标记。弗吉尼亚州、印第安纳州和威斯康星州的这些森林将提供东部温带森林的广泛地理样本。将对几个物种的幼苗和树苗的存活和生长进行为期两年的跟踪，以确定它们在随机选择的成年树周围的死亡率和生长率。这一结果将为温室研究的物种选择提供信息，以确定林中苗木成败的因素。研究人员预测，该群落中的稀有物种在早期生命阶段将比更常见的物种更容易受到病原体的影响。森林对可持续的人类社会至关重要，并提供了一种必不可少的可再生资源。因此，重要的是要了解森林如何生长和发展。这项研究将通过强调病原体驱动的死亡在森林社区结构中的作用，为森林系统的保护和管理工作提供信息。此外，它还将通过检查物种在纬度梯度上的表现的区域差异，提供气候变化可能如何影响森林更新的证据。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总体重要性。

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.