COLLABORATIVE RESEARCH: Ecosystem Response to N and Organic C Deposition from the Urban Atmosphere

未来30年的大部分人口增长将发生在城市地区。虽然人类活动对城市环境的影响最为强烈，但我们缺乏对城市生态系统中人为变化的生态反应的机制理解。该项目研究了大凤凰城土地和大气之间的化学元素交换，并提出了一个问题：城市元素循环在生态系统中是独一无二的吗？生态系统科学家、大气化学家和生物地球化学家正在验证这样一种假设，即不同的生物地球化学途径是由从大气到陆地的无机氮和有机碳沉积升高引起的。研究人员将研究营养沉积升高对生态系统的影响，测试解释生态系统反应的替代假设，并评估他们的发现是否可以推广到西南部和墨西哥的沙漠生态系统。该项目应用了一系列复杂的方法来解决一个与家庭息息相关的常见问题——大多数人居住的城市环境。这项工作与现有的长期生态研究项目对快速发展的凤凰城进行的环境调查密切相关。除了进行研究之外，科学家们还与包括部落领袖在内的当地决策者合作，解决快速扩张的城市边界日益恶化的环境质量问题。该项目还通过暑期实习项目为少数民族本科生提供培训，并通过独立研究为研究生和博士后学者提供培训。

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.