DISSERTATION RESEARCH: The effect of nitrogen deposition on plant community dynamics across local and regional scales

加州景观的快速城市化使残留的橡树稀树草原生态系统暴露在大气氮(N)沉积水平不断增加的环境中。沉积的氮进入生态系统，使植物暴露在它们可能不适应的氮的数量和化学形态中。氮沉积并不是在整个地貌上均匀分布，而是在多个尺度上有所不同。这导致了土壤中N的异质性分布，这可能会在增加N投入的情况下改变植物群落。这项研究的目的是调查氮沉降如何与在区域(例如降雨)和局部(例如光照)尺度上变化的环境条件相互作用，以构建植物群落。本研究将采用观测和实验相结合的方法来了解橡树稀树草原接受氮沉积和植物响应的模式和过程。本研究将研究通过N沉积影响橡树稀树草原植物群落的具体过程。了解嵌入在不断变化的景观中的自然区域的动态对于管理和保护工作至关重要。管理者们担心氮沉积对入侵物种的影响，以及这如何影响牧场的牧草质量。在更广泛的区域范围内，结果可以为影响氮排放和空气质量的土地使用和监管决策提供信息。

Rapid urbanization of California's landscape exposes remnant oak savanna ecosystems to increasing levels of atmospheric nitrogen (N) deposition. Deposited nitrogen enters the ecosystem and exposes plants to amounts and chemical forms of N that they may not be adapted to. Nitrogen deposition is not distributed evenly across the landscape, but varies across multiple scales. This results in the heterogeneous distribution of N in soil, which may alter plant communities under increasing N inputs. The aim of this research is to investigate how N deposition interacts with environmental conditions, which vary at the regional (e.g., rainfall) and local (e.g., light) scale, to structure plant communities. A combination of observational and experimental methods will be used to understand patterns and processes by which oak savannas receive N deposition and plants respond to it.This research will study specific processes through which N deposition affects plant communities in oak savannas. Understanding dynamics of natural areas embedded within a changing landscape is critical for management and conservation efforts. Managers are concerned about the effect of N deposition on invasive species and how that affects forage quality in grazing lands. At the broader, regional scale, results can inform land-use and regulation decisions affecting N emissions and air quality.