RAPID: Responses of herbaceous annual plants to material deposition from the urban atmosphere under contrasting conditions of antecedent drought and winter rainfall

沙漠是出了名的多变环境，有几年(相对)充足的降雨，还有一些非常干燥的条件。一年生草本植物的生长和丰度直接受到这种高变异性的影响，这些草本植物每年都是从前几年储存的种子中生长出来的。除了提供美丽的沙漠景观外，一年生草本植物也是沙漠土壤养分循环和有机物质积累的重要贡献者。研究人员一直在调查亚利桑那州凤凰城地铁汽车产生的氮氧化物等空气污染物如何影响索诺兰沙漠的长寿灌木，但他们获得了一个难得的机会来探索污染物对沙漠一年生植物的影响，因为在经历了十年的干旱后，2008年和2009年出现了两年高于平均水平的冬季降雨量。因此，将首次研究高降雨量和城市污染对一年生草本植物丰度、种类和化学组成的综合影响，这将有助于加深对多种因素如何单独和联合影响植物生长的理论和理解。发展对城市地区人类活动(主要与交通有关)对城市环境内部和顺风向沙漠过程的影响的理解。本科生将通过接触他们生活的栖息地的生态研究获得宝贵的经验。

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.