REU: LTREB: Short-term Climate Change and Variable Response to Disturbance in an Arid Land Watershed-stream Ecosystem

该项目包括对沙漠河流生态系统各组成部分应对干扰的能力的长期调查，这种干扰本身随着气候的年际变化而变化。气候与这个生态系统相互作用，通过径流向河道提供水和营养物质。特别是氮，沙漠生态系统的一个关键元素，随着长时间（几年）的干湿期的变化而在溪流中变化。氮的有效性对藻类演替和无脊椎动物受干扰后的恢复能力都有很强的影响。影响降水和径流的气候因素是这一生态系统的主要干扰形式，即山洪暴发和干旱。因此，气候通过影响降水、蒸散发和由此产生的径流，既改变了生态系统必需物质的输入，也是生物结构的主要破坏者。本文将采用操作和实验相结合的方法，对亚利桑那州Sycamore Creek地区的水陆联系机制和干扰响应的年际模式进行研究。这项研究将在很大程度上依赖并扩展描述该生态系统结构和功能的现有长期数据库。

This project comprises a long-term investigation of the capacity of various components of a desert stream ecosystem to respond to a disturbance which itself varies with interannual variation in climate. Climate interacts with this ecosystem by providing, through runoff, both water and nutrients to the stream channel. In particular, nitrogen, a key element in desert ecosystems, varies in stream water as a function of extended (several years) dry or wet periods. Nitrogen availability has a strong influence on both algal succession and the capacity of invertebrates to recover after disturbance. Climatic forcers affecting precipitation and runoff provide the predominant form of disturbance in this ecosystem, flash floods and drought. Therefore, climate, by influencing precipitation, evapotranspiration, and resulting runoff, both alters inputs of essential materials to the ecosystem and is a major disrupter of biotic structure. Both the mechanisms of terrestrial-aquatic linkage and interannual patterns of disturbance response in Sycamore Creek, Arizona, will be studied using a combination of manipulative and experimental approaches. This research will rely heavily upon and will extend an existing long-term database describing structure and functioning of this ecosystem.