I am broadly interested in all areas of ecosystem ecology. My research addresses: (1) the influence of changes in atmospheric composition, element cycling, and climate on ecosystem processes; (2) the effects of urbanization and suburbanization on biogeochemical cycles; and (3) the influence of diversity, especially plant species composition, on biogeochemical processes. In the area of global change, I aim to understand how human effects on global nutrient cycles affect carbon cycling and how variation in biodiversity, atmospheric carbon dioxide, nitrogen inputs, warming, and precipitation influence forest and grassland ecosystems. In the area of urban ecology, I am studying quantifying sources of nutrient pollutants to surface waters and patterns of biodiversity.