Prof. Bird's biogeochemistry lab is focused on below ground C, N and S cycling in terrestrial ecosystems. Soils are critical controllers on the flow of matter and energy in the environment and are considered especially important in the Earth's response to Global Change. Soils act as both a significant source of atmospheric greenhouse gases (i.e., carbon dioxide, methane and nitrous oxide) and as a sizable stable sink for plant C and N inputs. Our research group investigates how soil microbial communities, plants, climate and mineralogy interact to control the turnover, loss or stabilization of soil C and N in temperate and tropical ecosystems. The Bird lab uses stable isotopic tracers (13C and 15N) to follow C and N among plants, soil microbes, and mineral surfaces to better understand how soils support ecological productivity and environmental quality.