Nutrient effects on a detritus-based stream ecosystem at the Coweeta Hydrologic Laboratory from 1998 to 2003

To determine the effects of nutrient enrichment in a detritus-based stream, we have continuously enriched a headwater stream with N and P for 4.5 years and quantified the response at different scales of stream structure and function: microbial, metazoan, and ecosystem. The effects of enrichment in the treatment stream (Watershed 54, WS54) were compared to conditions in the reference stream (Watershed 53, WS53) and one year of comprehensive baseline sampling was conducted in both streams prior to enrichment. Our first objective was to assess the effects of nutrient enrichment on growth and production of organisms. Our second objective was to determine the effects of nutrients on the fate of carbon resources, which were altered via increased microbial metabolism and invertebrate consumption.

为探明碎屑基溪流（detritus-based stream）中的营养富集效应，我们对一条源头溪流连续4.5年施加氮（N）与磷（P）富集处理，并从溪流结构与功能的不同尺度——微生物、后生动物与生态系统尺度——量化其响应。我们将处理溪流（54号集水区，WS54）的富集效应与对照溪流（53号集水区，WS53）的环境条件进行对比；在启动富集处理前，已对两条溪流开展了为期1年的综合性基线采样。本研究的首要目标为评估营养富集对生物生长与生产力的影响，次要目标为明确营养物质对碳资源归趋的调控作用，而碳资源的归趋会因微生物代谢水平提升与无脊椎动物取食活动发生改变。