Deserts are notoriously variable environments, with some years of (relatively) abundant rainfall and others of very dry conditions. The growth and abundance of annual herbaceous plants, which grow each year from seeds deposited in previous years, are directly affected by this high variability. Besides providing beautiful desert landscapes, annual herbaceous plants also are important contributors to the cycling of nutrients and build-up of organic material in desert soils. Researchers have been investigating how air pollutants such as nitrogen oxides produced by automobiles in metro Phoenix, Arizona, affect long-lived shrubs of the Sonoran Desert, but were presented with a rare opportunity to explore pollutant effects on desert annual plants because two years of above-average winter precipitation occurred in 2008 and 2009, following a decade of drought. Thus, for the first time, the combined effects of high rainfall and urban pollution on the abundance, kinds, and chemical makeup of annual herbaceous plants will be studied, and this will help advance theory and understanding of how multiple factors affect plant growth singly and in combination.
Developing an understanding of the impact of human activities (largely transportation-related) in urban areas on desert processes both within and downwind from the urban environment. Undergraduate students will gain invaluable experience through their exposure to ecological research in the habitat in which they live.
National Science Foundation. Division of Environmental Sciences
June 2009 - August 2010