Pathogen mediated diversity and response to climate change

真菌病原体被认为通过竞争性优势物种的选择性死亡来控制森林树木的生物多样性，否则会威胁到竞争力较弱的物种。因此，气候变暖可能增加疾病的范围和严重程度。随着病原体越来越多地在温和的冬季存活，繁殖率增加，植物防御遭受干旱和温度胁迫。这项研究将评估病原菌调节树木幼苗健康的程度，确定所涉及的真菌及其对树木生长和存活的影响，并确定这些相互作用如何受到本世纪中叶预测的温度变化的影响。这项研究将确定当温度升高时，在与其他树种同时竞争的背景下，温度如何影响它们的宿主，使用一个变暖实验，在北卡罗来纳州和马萨诸塞州，树苗暴露在土壤和空气温度升高3°C到5°C的环境中。一旦幼苗出现，发芽、存活、疾病症状和生长都将被监测。寄生在种子和幼苗上的致病真菌和卵菌将通过结合培养和基于DNA序列的方法进行鉴定。将使用考虑温度、病原体和与其他树木竞争组合的模型来评估变暖对病原体发病率、感染和幼苗数量的影响。通过将不同来源的数据整合到分析中，这项研究将深入了解森林风险的基本生物学，因为树木保护自己的自然能力在变暖的气候下发生了变化。本研究将深入了解植物病原体在自然系统中的时空动态，以及这些动态在气候变暖下可能发生的变化。提高对植物病原体种群的多样性和组成以及环境因素的了解，既可以加强当前的管理实践，也可以为未来树木分布的模型提供信息。教学、培训和学习将是这项研究的组成部分，因为它需要本科生和高中生作为勤工俭学助理和暑期研究技术人员的协助。此外，将启动基于调查的数据收集部分，以吸引K-12和感兴趣的公众，将这种多样性研究与杜克森林支持的外展活动相结合。这项研究的结果将在一年一度的杜克森林研究日期间向高中生传播，并在杜克森林的一系列森林病理学远足中向公众传播。

Fungal pathogens are thought to control biodiversity of forest trees through selective mortality of competitively dominant species that would otherwise threaten less competitive species. Climate warming may thus increase the extent and severity of disease. As pathogens increasingly survive mild winters, reproductive rates increase and plant defenses suffer from drought and temperature stress. This research will assess the extent to which pathogens regulate tree seedling health, identify the fungi involved and their effects on tree growth and survival, and determine how those interactions are affected by the temperature changes predicted for mid-century. The study will determine how temperatures affect their hosts when temperatures increase, within the context of simultaneous competition from other tree species, using a warming experiment where tree seedlings are exposed to soil and air temperature increases of 3°C to 5°C in North Carolina and Massachusetts. Once seedlings emerge, germination, survival, disease symptoms, and growth will be monitored. Pathogenic fungi and oomycetes residing on both seeds and seedlings will be identified using a combination of culture and DNA sequence-based methods. The effects of warming on pathogen incidence, infection, and seedling demography will be assessed using models that account for the combination of temperature, pathogens, and competition with other trees. By incorporating different sources of data into the analyses, this research will provide insight into the basic biology of forest risk as the natural capacity of trees to defend themselves changes under a warmer climate. The proposed research will provide insight into spatial and temporal dynamics of plant pathogens in natural systems, and how these dynamics might change under a warmer climate. An improved understanding of the diversity and composition of populations of plant pathogens and environmental factors can both enhance current management practices and inform models of future tree distributions. Teaching, training, and learning will be an integral part of this study, as it will require the assistance of undergraduate and high school students as work-study assistants and summer research technicians. In addition, a survey-based data collection component will be initiated to engage K-12 and the interested public, which combines this diversity research with outreach activities supported by Duke Forest. The results of this study will be disseminated to high school students during the annual Duke Forest Research Days, and to the general public in a series of forest pathology hikes in the Duke Forest.