Stream Ecosystem Response to Decoupling Terrestrial-Aquatic Linkages

华莱士河生态系统对陆水联系解耦的响应本项目涉及水源的木材去除和持续的叶片排除。在过去的3年里，在180米的河流中，与正常输入树叶的河流相比，树叶被排除在外导致动物产量下降，转向替代食物，藻类的相对重要性增加，小有机和无机颗粒的出口增加，河流中溶解有机碳（DOC）的产生减少，营养吸收长度更长。有些结果出乎意料，如无机基质和木材上的微生物活性增强，有机质质量和养分输出均未下降。生长在木材和无机基质表面的微生物生物膜，以及增加的藻类生长，现在是叶片排斥流中重要的营养汇。木材仍然是陆源有机质的一种显著而普遍的形式。该项目将继续排除叶片，去除小木材（第1年）和大木材（第3年），以减少：a)木材上代谢活跃的微生物生物膜，b)溪流的物理稳定性，c)颗粒和营养物质的保留，d)大量但难处理的陆地输入（木材）。两阶段操作允许研究者区分溪流中木材的食物资源作用和结构作用。对这种以碎屑为基础的食物网进行长期的生态系统级操作，将提高对河流生态系统结构和功能的重要陆地联系作用的普遍理解。

9629268 Wallace Stream Ecosystem Response to Decoupling Terrestrial-Aquatic Linkages This project involves wood removal and continued leaf exclusion from a headwater stream. During the last 3 years, leaf exclusion from a 180 meter reach of stream has resulted in decreased animal production, shifts to alternative foods, increased relative importance of algae, increased export of small organic and inorganic particles, less within stream dissolved organic carbon (DOC) generation, and longer nutrient uptake lengths compared to a stream with normal inputs of leaves. Some results were unexpected, such as greater microbial activity on inorganic substrates and wood and no decrease in either organic matter quality or nutrient export. Microbial biofilms, growing on the surfaces of wood and inorganic substrates, and increased algal growth are now important nutrient sinks in the leaf exclusion stream. Wood remains a conspicuous and prevalent form of terrestrially derived organic matter. This project will continue leaf exclusion and remove small (year 1) and large wood (year 3) to reduce: a) metabolically active microbial biofilms on wood, b) physical stability of the stream, c) particle and nutrient retention, and d) a large but refractory (wood) terrestrial input. The two stage manipulation allows the investigators to distinguish the food resource role and structural role of wood in streams. This long-term, ecosystem-level manipulation on this detritus-based food web will improve general understanding of the role of important terrestrial linkages to the structure and function of stream ecosystems.