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.
