UNC Ecology Seminar: Rebecca McCulley

Climate change (altered CO2, warming, and altered precipitation) may affect plant-microbial interactions, such as the Lolium arundinaceum – Neotyphodium coenophialum symbiosis, to alter future ecosystem structure and function. To assess this possibility, tall fescue tillers and various ecosystem responses were monitored at two climate manipulation experiments: one in an old field community in Tennessee, and the second in a managed grassland/pasture system in central Kentucky. In the Tennessee experiment, endophyte infection frequency (EIF) of tall fescue tillers was determined, and infected (E+) and uninfected (E-) tillers were analyzed for tissue chemistry. EIF of tall fescue was higher under elevated CO2 (91% infected) compared to ambient (81%) but was not impacted by warming or precipitation treatments. Within E+ tillers, elevated CO2 decreased alkaloid concentrations of both ergovaline and loline, by ~30%; whereas warming increased loline concentrations 28% but had no effect on ergovaline. In the Kentucky experiment, E+ and E- tiller growth and tissue chemistry was followed for a year. While strong climate treatment effects were observed on tiller growth, these effects were largely independent of endophyte status. However, tillering rate, mortality, and tissue chemistry were sensitive to endophyte effects and interactions with climate. These results indicate that the fungal endophyte – grass symbiosis is sensitive to projected climate change and will likely play a role in governing ecosystem responses (e.g., litter decomposition, insect herbivory, and plant species composition) to future climatic conditions.