Streams store nutrients in standing stocks of organic matter (OM) and associated biologically sequestered elements. Unlike standing stocks of autotrophs, detritus is depleted by nutrient enrichment, potentially reducing areal storage of detritus-associated nutrients. To test effects of nutrient-loading on storage of nitrogen (N) and phosphorus (P) by autotrophic and detrital-pool compartments, we quantified the effects of 2 yr of continuous experimental N and P additions on fine benthic organic matter (FBOM), leaves, wood, and biofilms in five forest streams. Our design tested the relative strength of N vs. P on OM nutrient content, areal OM storage, and areal nutrient storage in OM types. Enrichment increased nutrient content of all OM types; %P increased more than %N in leaves, wood, and biofilms, but not FBOM. Biofilm %P and %N increased more than in all detrital types. Areal FBOM and leaf storage declined with nutrient enrichment. Biofilm standing stocks were generally higher with enrichment but were not related to the streamwater N and P gradients. Despite increased OM nutrient content, total areal nutrient storage in leaves and wood decreased due to reduced OM storage. Although annual nutrient storage was stabilized by FBOM, seasonal variation in nutrient storage increased with enrichment. Leaf-associated nutrient storage was reduced in most seasons, whereas FBOM and biofilm nutrient storage increased in winter and spring, respectively, relative to pretreatment. Overall, the combined responses of all OM types to enrichment resulted in reduced storage and altered seasonal availability of carbon and nutrients, which has implications for consumers and downstream processes.

中文翻译：

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森林溪流的实验性营养富集减少了生态系统氮和磷的储存

溪流将营养物质储存在有机质 (OM) 和相关生物隔离元素的常备库存中。与自养生物的常备种群不同，碎屑会因营养物质富集而耗尽，从而可能减少碎屑相关营养物质的面积储存。为了测试养分负荷对自养和碎屑池隔室储存氮 (N) 和磷 (P) 的影响，我们量化了 2 年连续实验添加 N 和 P 对细底栖有机质 (FBOM) 的影响，五条森林溪流中的树叶、木材和生物膜。我们的设计测试了氮与磷对 OM 养分含量、面积 OM 储存量和 OM 类型的面积养分储存量的相对强度。浓缩增加了所有 OM 类型的营养成分；叶子、木材和生物膜中 %P 的增加量超过 %N，但 FBOM 中的 %P 增加量不超过 %N。生物膜 %P 和 %N 的增加幅度高于所有碎屑类型。面积 FBOM 和叶片储存量随着养分富集而下降。随着富集，生物膜常存量通常较高，但与溪流 N 和 P 梯度无关。尽管 OM 养分含量增加，但由于 OM 储存量减少，叶子和木材中总面积养分储存量减少。尽管 FBOM 稳定了年度养分储存量，但养分储存量的季节性变化随着富集而增加。与预处理相比，大多数季节叶片相关养分储存量减少，而冬季和春季 FBOM 和生物膜养分储存量分别增加。总体而言，所有 OM 类型对富集的综合反应导致储存量减少并改变了碳和养分的季节性可用性，