Most population growth during the next 30 years will occur in urban areas. Although human activities affect the environment most intensely in cities, we lack a mechanistic understanding of ecological response to human-wrought changes in urban ecosystems. This project studies the exchange of chemical elements between land and atmosphere in Greater Phoenix and asks: Are urban elemental cycles unique among ecosystems? Ecosystem scientists, atmospheric chemists, and biogeochemists are testing the hypothesis that distinct biogeochemical pathways result from elevated inorganic nitrogen and organic carbon deposition from atmosphere to land. Researchers will examine ecosystem-level consequences of elevated nutrient deposition, test alternative hypotheses to explain ecosystem response, and evaluate whether their findings can be generalized to desert ecosystems in the Southwest and Mexico.
The project applies a range of sophisticated methods to a common problem that is close to home-the urban environment in which most humans live. The work is closely coupled with ongoing environmental investigations of rapidly growing Phoenix by an existing Long-Term Ecological Research project. In addition to conducting research, scientists are working with local decision makers, including tribal leaders, to address worsening environmental quality on the borders of rapidly expanding cities. The project also provides training for minority undergraduate students through a summer internship program, and for graduate students and a post-doctoral scholar through independent research.