Estimating changes in organic matter flow from resource to consumer using trophic basis of production (TBP) is a way to examine resource limitation effects on ecosystem function. We examined diet shifts and production of insect detritivores to assess changes with reduced detrital inputs to a forested headwater stream. Organic matter was excluded for 7 years using a canopy net. Small and large wood were removed from the stream after the 3rd and 5th year, respectively. Detritivore production declined after 3 years of litter exclusion. After wood removal, production of detritivores declined again. Steepest declines in Pycnopsyche gentilis production occurred within year 1. Tipula spp. and Tallaperla spp. production declined after wood removal. Diets shifted from leaves to wood to fine particulate organic matter (FPOM) for Tipula spp. and Tallaperla spp., but not for P. gentilis . Resource flows to detritivores shifted in the exclusion stream from leaves to wood to FPOM after leaf standing crops declined and wood removal. Small wood was an important food resource. TBP results showed shifts in food resource use by two detritivores with terrestrial input reduction. These findings suggest that maintaining diverse riparian inputs of organic matter is important for detritivore productivity in forested headwater watersheds.

中文翻译：

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随着森林投入减少，河流有害生物生产的营养基础发生变化

使用生产的营养基础 (TBP) 估算从资源到消费者的有机物质流量变化是一种检查资源限制对生态系统功能影响的方法。我们检查了饮食变化和昆虫碎屑的产生，以评估减少对森林源头溪流的碎屑输入的变化。使用天篷网排除有机物质 7 年。分别在第 3 年和第 5 年之后从溪流中移走小木头和大木头。经过 3 年的垃圾排除后，食腐动物的产量下降。木材去除后，碎屑的产量再次下降。Pycnopsyche gentilis 产量下降幅度最大的是第 1 年。Tipula spp。和 Tallaperla 属。砍伐木材后产量下降。Tipula spp 的饮食从树叶转向木材，再到细颗粒有机物 (FPOM)。和 Tallaperla spp.，但不适用于 P. gentilis。在立叶作物减少和木材去除后，流向碎屑动物的资源从叶子到木材转移到 FPOM。小木头是重要的食物资源。TBP 结果显示，随着陆地投入减少，两种食腐动物的食物资源使用发生了变化。这些发现表明，保持河岸有机物质的多样化输入对于森林源头流域的碎屑动物生产力很重要。