Dissertation Research: The Effects of Heterogeneity and Scale on Nutrient Dynamics in a Desert Stream

9800912格林：公共政策研究所建议在河流-河岸生态系统的不同尺度上研究空间结构对营养物质动态的影响。溪流是将营养物质从陆地高地输送到湖泊、水库、地下水含水层和河口的异质生态系统。养分被保留、运输或转化的程度取决于水通过生态系统组成部分或斑块的路径，以及在每个斑块中的停留时间。初步结果表明，与传统看法相反，溪水中的营养物质浓度在空间上是高度可变的。PIs将描述一系列空间尺度上溪流地表水中养分浓度的模式，确定生态系统结构的元素和相关过程，以解释每个尺度上的这些模式，并开发基于空间结构的模拟模型，以预测作为空间结构函数的养分浓度和养分保留量。这项研究将通过研究异质性和导致异质性的过程如何随着特定生态系统中的规模变化来为新兴的生态学理论做出贡献。它还将通过增加我们对沙漠溪流集水区营养动态的了解，并通过提供一个模拟模型用于未来的生态系统研究，从而帮助溪流生态系统管理。

9800912 Grimm The PIs propose to investigate the effects of spatial structure on nutrient dynamics at different scales in a stream-riparian ecosystem. Streams are heterogeneous ecosystems that transport nutrients from terrestrial uplands to lakes, reservoirs, groundwater aquifers and estuaries. The extent to which nutrients are retained, transported, or transformed depends on the path of water through ecosystem components, or patches, and residence time in each patch. Preliminary results show that, contrary to conventional wisdom, nutrient concentrations in stream water are highly variable in space. The PIs will describe the pattern of nutrient concentrations in stream surface water over a range of spatial scales, identify elements of ecosystem structure and associated processes that might explain these patterns at each scale, and develop a spatial structure-based simulation model to predict nutrient concentrations and nutrient retention as a function of spatial structure. The research will contribute to emerging ecological theory by examining how heterogeneity and the processes that cause it change with scale in a particular ecosystem. It will also aid in stream ecosystem management by increasing our understanding of nutrient dynamics in a desert stream catchment and by providing a simulation model for use in future ecosystem studies.