Despite abounding evidence that leaf litter traits can predict decomposition rate, the way these traits influence trophic efficiency and element transfer to higher trophic levels is not resolved. Here, we used litter labeled with ¹³C and ¹⁵N stable isotopes to trace fluxes of litter C and N from four leaf types to freshwater invertebrate communities. We measured absolute (mg C or N) and relative assimilation (percentage of litter C or N incorporated into invertebrate biomass relative to C and N lost during decomposition). Four patterns emerged: (1) Invertebrate communities assimilated more C and N from slowly decomposing litter than communities feeding on rapidly decomposing litter; (2) absolute assimilation of both C and N in leaf packs was positively correlated with the relative biomass of invertebrate taxa in leaf packs; (3) Chironomidae larvae, which colonize packs in the early decomposition stages, assimilated the most C and N by the end of the 35-day experiment; and (4) most taxa, spanning five functional feeding groups (collector–gatherers, shredders, collector–filterers, scrapers, and predators), showed similar patterns in both absolute and relative assimilation across leaf types. These results challenge traditional views of litter quality by demonstrating that trophic efficiency is negatively associated with decomposition rate across these four leaf types.

尽管有大量证据表明叶片凋落物性状可以预测分解速率，但是这些性状影响营养效率和将元素转移到较高营养水平的方式尚未得到解决。在这里，我们使用了标有¹³ C和^15的垃圾N个稳定同位素可追踪凋落物C和N从四种叶片类型到淡水无脊椎动物群落的通量。我们测量了绝对值（mg C或N）和相对同化率（掺入无脊椎动物生物量中的凋落物C或N相对于分解过程中损失的C和N的百分比）。出现了四种模式：（1）与以快速分解的垃圾为食的社区相比，无脊椎动物社区从缓慢分解的垃圾中吸收了更多的C和N；（2）叶包中C和N的绝对同化与叶包中无脊椎动物类群的相对生物量呈正相关；（3）在35天实验结束前，在分解早期定居的Chi虫科幼虫吸收了最多的碳和氮；（4）大多数分类单元，涵盖五个功能性喂养组（收集器-收集器，切碎机，收集器-过滤器，刮刀和掠食者）在不同叶片类型的绝对和相对同化中显示出相似的模式。这些结果证明了营养效率与这四种叶子类型的分解速率负相关，从而挑战了传统的凋落物质量观点。