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

Indiana University, Bloomington IN

Investigators

Abstract

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.