DISSERTATION RESEARCH: The role of seedling pathogens in temperate forest recuitment

长期以来，植物病原体一直被怀疑通过控制幼苗的生长和存活来维持树木的多样性，但对未经管理的温带森林中的病原体知之甚少。为了更好地了解森林病原体如何影响树种的共存，在北卡罗来纳州的两个森林中种植了混合树种的树苗。经常监测苗木死亡情况，并使用培养和DNA方法从死亡的苗木中鉴定病原体。同时收集有关树木人口统计学(苗木死亡率、成虫密度)和环境条件(光照、土壤湿度)的其他相关数据。这些数据结合在一起，以确定这些森林中的主要真菌和卵菌病原体，它们分布背后的环境因素，以及它们在塑造森林群落中所起的作用。该项目有助于了解植物病原体的空间和时间动态，有助于减少其对自然和管理森林生态系统的负面影响。这些信息具有重要的经济意义，可以用来改进有关在森林或恢复地区种植和收获的密度、位置和时机的决策，以便制定新的疾病管理战略，促进植物生产力和可持续性的提高。这项研究有可能加强当前的管理实践，并为预测未来与全球变化相关的树木分布的模型提供信息。该项目还通过让本科生和高中生担任勤工俭学助理和暑期研究技术人员来促进外联、教学和培训。

Plant pathogens have long been suspected to play a role in maintaining tree diversity by controlling seedling growth and survival, yet relatively little is known about pathogens in unmanaged temperate forests. To better understand how forest pathogens influence coexistence of tree species, mixed-species plots of tree seedlings were planted in two North Carolina forests. Seedling mortality is monitored frequently, and pathogens are identified from dead seedlings using cultural and DNA-based methods. Other relevant data about tree demography (seedling mortality, adult density) and environmental conditions (light, soil moisture) are collected simultaneously. These data are combined to identify the major fungal and oomycete pathogens in these forests, the environmental factors underlying their distributions, and the role they play in shaping forest communities. This project provides insight into understanding the spatial and temporal dynamics of plant pathogens, which may help to reduce their negative impact in natural and managed forest ecosystems. This information is of economic significance and can be used to improve decisions about the density, location, and timing of planting and harvesting in forests or restoration areas such that new disease management strategies can be developed that promote increased plant productivity and sustainability. This study has the potential to enhance current management practices and to inform models that predict future tree distributions associated with global change. This project also promotes outreach, teaching and training by involving undergraduate and high school students as work-study assistants and summer research technicians.