REU: Stability of a Stream Ecosystem to Disturbance by Flooding and Drying

调查人员将研究一条溪流 生态系统是能量和氮的源或汇， 大沙漠景观 能量流将被总结为 初级生产与呼吸（P/R）和氮的比值 以固氮与反硝化之比循环 （F/D）。 判断一个系统是源还是汇， 生成嵌套层次，从藻类 整个排水系统。 结果将部分测试 蒸汽生态学分层方法的效用。 山洪和干旱产生的扰动效应， 不同水文极端的每个特征，将是 在等级制度的背景下进行研究。 子系统稳定性 将在每一次干扰面前进行评估， 两者的组合。 详细研究表面和潜流之间的相互作用 涉及有机碳和无机氮的区域将被 用于探索子系统相互作用如何影响 每个人的稳定性。 假设垂直交换 增强了两个子系统的弹性。 最后，将使用模拟模型来模拟 扰动对整个排水系统的影响。 结果将显示几年的干扰制度 影响溪流与邻近生态系统的联系： 下游水库、地下蓄水层或平行河岸 社区. 调查人员完全有资格执行这项建议 研究计划，有足够的设施，并有一个良好的 出版记录。

The investigators will study the extent to which a stream ecosystem is a source or sink for energy and nitrogen in the larger desert landscape. Energy flow will be summarized as the ratio of primary production to respiration (P/R) and nitrogen cycling as the ratio of dinitrogen fixation to denitrification (F/D). Judgments of whether a system is a source or sink will be generated for nested hierarchys, ranging from the algal assemblage to the entire drainage. Results will test in part the utility of hierarchical approaches to steam ecology. Disturbance effects generated by flash flooding and drying, each characteristic of a different hydrologic extreme, will be studied in the context of the hierarchy. Stability of subsystems will be evaluated in the face of each disturbance and combinations of the two. Detailed study of interactions between surface and hyporheic zones involving organic carbon and inorganic nitrogen will be used to explore how subsystem interaction influences the stability of each. The hypothesis is that vertical exchange enhances resilience of both subsystems. Finally, a simulation model will be used To simulate the effect of disturbance regimes on the whole drainage system. Results will show how disturbance regimes of several years length influence the linkage of streams with adjacent ecosystems: downstream reservoirs, groundwater aquifers, or parallel riparian communities. The investigators are well qualified to run the proposal research program, have adequate facilities and have an excellent publication record.