The productivity of an ecosystem depends on the recycling of nutrients through the process of decomposition. Decomposition is primarily governed by climate and the chemical composition of plant litter. Traditionally, decomposition rates have been estimated using concentrations of carbon, nitrogen and lignin in the litter. However, the structural characteristics of many hard-to-degrade compounds (biopolymers), including lignins, tannins and cuticular matrices, can dictate overall decomposition rates. The climate in which plants grow can strongly influence the structural properties of these compounds. Climate change thus has the potential to alter decomposition both directly, by changing temperature and moisture, and also indirectly, by changing the structural attributes of biopolymers in plant litter, in ways that are not factored into traditional nutrient cycling models. This project has three long-term goals. The first goal is to learn how growing season temperature and moisture availability affect the diversity and chemical properties of biopolymers that govern decomposition of plant litter. The second goal is to understand how environmental conditions interact with the chemical composition of litter to affect decomposition and nutrient cycling. The third goal is to develop and test models of decomposition that incorporate new knowledge of the roles of climate and biopolymer properties. The investigators will test these hypotheses using six plant species from the Boston-Area Climate Experiment, which exposes patches of old fields with tree seedlings to twelve possible future climates. Results from this project will improve predictions of carbon and nitrogen cycling in a changing climate. The results will have application beyond soil nutrient dynamics, as tannins are relevant to food quality (as antioxidants), fodder quality and herbivory (as deterrents). The project will provide undergraduates with opportunities for creative inquiry and a new course offering, and will develop a summer course for in-service K-12 teachers and non-formal educators. The project also will provide learning and research experiences to high school students and students from the minority college in the state through the South Carolina Life program.
