Stream Ecosystem Response to Decoupling Terrestrial-Aquatic Linkages

9629268 华莱士 河流生态系统对陆-水关系解耦的响应 该项目涉及从源头河流中清除木材和继续排除树叶。在过去的3年中，叶排除从180米的流达到导致动物生产减少，转向替代食品，增加藻类的相对重要性，增加出口的小有机和无机颗粒，流内溶解有机碳（DOC）的生成较少，和更长的营养吸收长度相比，流与正常输入的叶。 有些结果是出乎意料的，如无机基质和木材上的微生物活动更大，有机物质量或营养输出没有下降。 生长在木材和无机基质表面的微生物生物膜，以及藻类生长的增加，现在是排叶流中重要的营养汇。木材仍然是陆地来源的有机物质的一种显著和普遍形式。 该项目将继续排除叶子并去除小木材（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）颗粒和养分保留，以及d）大量但难降解的（木材）陆地输入。 这两个阶段的操作允许调查人员区分食物资源的作用和木材在溪流中的结构作用。 对这种以碎屑为基础的食物网进行长期的生态系统一级的操纵，将提高对重要的陆地联系对河流生态系统的结构和功能的作用的普遍认识。

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.