DISSERTATION RESEARCH: Vegetation Effects on Nitrogen Cycling Hotspots in an Alpine-Subalpine Ecosystem

人类燃烧化石燃料和使用氮肥，使全球向大气和自然生态系统输入氮的速度增加了一倍。这些更高的氮投入导致了许多环境问题，包括空气污染、酸雨、气候变化、入侵物种数量增加和生物多样性丧失。为了帮助理解和管理这些环境问题，研究人员基于小尺度的测量，对生态系统中氮的处理方式有了详细的了解。这些小规模的测量虽然构成了重要的基础，但可能不能代表整个景观，特别是在山区。在这项研究中，研究人员致力于在景观尺度上理解高山-亚高山生态系统中的氮循环。该研究旨在定位丹佛市区附近落基山脉南部Niwot Ridge的高山-亚高山生态系统中氮循环的热点（异常活跃的区域）。该研究将探讨生物和非生物因素在控制氮循环速率中的相对作用。为了实现这些目标，研究人员将结合现场收集和遥感数据，测量整个景观的氮循环速率，这些数据描述了物理、化学和生物条件。本研究将有助于：(1)了解不同景观中氮循环速率变化的基本知识；(2)为负责制定影响山地生态系统自然资源的人类氮排放限制的土地管理机构提供信息；(3)发展更大空间尺度生态测量的新方法。

By burning fossil fuels and using nitrogen fertilizers, humans have doubled the global rate of nitrogen inputs to the atmosphere and natural ecosystems. These higher nitrogen inputs contribute to a multitude of environmental problems including air pollution, acid rain, climate change, higher abundance of invasive species, and biodiversity loss. To aid in understanding and managing these environmental problems, researchers have developed a detailed understanding of how nitrogen is processed in ecosystems based on small-scale plot-based measurements. While forming an important foundation, these small-scale measurements may not be representative of whole landscapes, especially in mountains. In this study, the investigators work toward a landscape-scale understanding of nitrogen cycling in an alpine-subalpine ecosystem. The research seeks to locate hotspots (unusually active areas) of nitrogen cycling within an alpine-subalpine ecosystem on Niwot Ridge in the southern Rocky Mountains, near the Denver metropolitan region. The research will address the relative roles of biological and non-biological factors in controlling nitrogen cycling rates. To accomplish these goals, the investigators will measure nitrogen cycling rates across the landscape in conjunction with field-collected and remotely-sensed data that describe physical, chemical, and biological conditions.This research will contribute to: (1) basic knowledge of variation in nitrogen cycling rates across diverse landscapes; (2) information for land management agencies responsible for setting limits on human nitrogen emissions that influence natural resources in mountain ecosystems; and (3) development of new methods for ecological measurements at larger spatial scales.