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

通过燃烧化石燃料和使用氮肥，人类使全球对大气和自然生态系统的氮素输入速度翻了一番。这些较高的氮素输入导致了一系列环境问题，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，研究人员基于小规模的地块测量，对生态系统中氮的处理方式进行了详细的了解。虽然形成了一个重要的基础，但这些小范围的测量可能并不能代表整个景观，特别是在山区。在这项研究中，研究人员致力于从景观尺度上了解高山-亚高山生态系统中的氮循环。这项研究试图定位落基山脉南部Niwot Ridge上高山-亚高山生态系统中氮循环的热点(异常活跃的区域)，靠近丹佛大都市区。这项研究将探讨生物和非生物因素在控制氮循环速率方面的相对作用。为了实现这些目标，研究人员将结合描述物理、化学和生物条件的野外收集和遥感数据来测量整个景观的氮循环速率。这项研究将有助于：(1)关于不同景观中氮循环速率变化的基本知识；(2)为负责设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；以及(3)开发更大空间尺度上的生态测量新方法。

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.