Abstract Plant traits are known to control litter decomposition rates through afterlife effects on litter quality. Land-use practices that modify plant traits, e.g. livestock grazing and soil fertilization, also have cascading effects on litter decomposition. However, almost all studies of these afterlife effects ignored the role of soil detritivores in the decomposition processes. We explored how the feeding activities of a macroarthropod modify microbial activity in leaf litter. Dead leaves from two grassland species, Bromopsis erecta and Potentilla verna, were collected in fertilized or unfertilized grazed plots and fertilized or unfertilized ungrazed plots. We determined how intraspecific variation in litter quality in response to sheep grazing and soil fertilization (i) influences the consumption and assimilation of leaf litter by the millipede Glomeris marginata, and (ii) affects the activity of microbial decomposers, assessed by substrate-induced respiration (SIR), in leaf litter before consumption and in faecal pellets and litter remains processed by Glomeris under all treatments. In the absence of millipedes, microbial activity was significantly higher in leaf litter from fertilized plots. Glomeris consumed larger amounts of leaf litter from fertilized grazed plots, owing to increased consumption of the otherwise poorly palatable Bromopsis, and produced larger amounts of faecal pellets when fed on this food. However, irrespective of the food consumed, SIR in faecal pellets was found to be similar in all treatments. Moreover, SIR in litter remains unconsumed at the end of the experiment was reduced to low and similar levels in all treatments. Overall, homogenization of microbial activity by Glomeris suppressed differences in SIR between leaf litter from fertilized and unfertilized plots, in both Bromopsis and Potentilla. Our results suggest that studies that assess afterlife effects of plant traits on decomposition using methods that exclude soil macrofauna may prove inadequate in ecosystems with abundant populations of detritivores.

中文翻译：

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以垃圾为食的大型节肢动物是否会破坏土地利用对微生物分解活动的连锁效应？

摘要 已知植物性状通过来世对凋落物质量的影响来控制凋落物分解率。改变植物特性的土地利用做法，例如牲畜放牧和土壤施肥，也会对凋落物分解产生连锁效应。然而，几乎所有关于这些来世影响的研究都忽略了土壤碎屑在分解过程中的作用。我们探索了大型节肢动物的摄食活动如何改变落叶中的微生物活动。在已施肥或未施肥的放牧地块以及已施肥或未施肥的未放牧地块中收集来自两种草原物种的枯叶，即 Bromopsis挺立和 Potentilla verna。我们确定了响应绵羊放牧和土壤施肥的凋落物质量的种内变化（i）如何影响千足虫 Glomeris marginata 对凋落物的消耗和同化，以及（ii）影响微生物分解者的活动，通过基质诱导的呼吸进行评估(SIR)、食用前的落叶和粪便颗粒中以及在所有处理下都由 Glomeris 处理的垃圾。在没有千足虫的情况下，受精地块落叶中的微生物活性显着更高。Glomeris 从施肥的放牧地块中消耗了大量的落叶，这是由于对其他可口的 Bromopsis 的消耗增加了，并且在以这种食物为食时产生了大量的粪便颗粒。然而，无论吃什么食物，发现粪便颗粒中的 SIR 在所有处理中都相似。此外，在实验结束时，垫料中的 SIR 仍未被消耗掉，在所有处理中都降至低且相似的水平。总体而言，Glomeris 对微生物活性的均质化抑制了 Bromopsis 和 Potentilla 中受精和未受精地块的凋落物之间的 SIR 差异。我们的结果表明，使用排除土壤大型动物群的方法评估植物性状对分解的来世影响的研究可能证明在具有丰富食腐动物种群的生态系统中是不够的。Glomeris 对微生物活性的均质化抑制了 Bromopsis 和 Potentilla 中受精和未受精地块的凋落物之间 SIR 的差异。我们的结果表明，使用排除土壤大型动物群的方法评估植物性状对分解的来世影响的研究可能证明在具有丰富食腐动物种群的生态系统中是不够的。Glomeris 对微生物活性的均质化抑制了 Bromopsis 和 Potentilla 中受精和未受精地块的凋落物之间 SIR 的差异。我们的结果表明，使用排除土壤大型动物群的方法评估植物性状对分解的来世影响的研究可能证明在具有丰富食腐动物种群的生态系统中是不够的。