Data from: Plant-litter-soil feedbacks in common grass species are slightly negative and only marginally modified by litter exposed to insect herbivory

Purpose Insect herbivory affects plant growth, nutrient and secondary metabolite concentrations and litter quality. Changes to litter quality due to insect herbivory can alter decomposition, with knock on effects for plant growth mediated through the plantlitter- soil feedback pathway. Methods Using a multi-phase glasshouse experiment, we tested how changes in shoot and root litter quality of fast- and slow-growing grass caused by insect herbivores affect the performance of response plants in the soil in which the litter decomposed. Results We found that insect herbivory resulted in marginal changes to litter quality and did not affect growth when plants were grown with fast- versus slow-growing litter. Overall, presence of litter resulted in reduced root and shoot growth and this effect was significantly more negative in shoots versus roots. However, this effect was minimal, with a loss of c. 1.4% and 3.1% dry weight biomass in roots versus shoots, respectively. Further, shoot litter exposed to insect herbivory interacted with response plant identity to affect root growth. Conclusions Our results suggest that whether litter originates from plant tissues exposed to insect herbivory or not and its interaction with fast- versus slow-growing grasses is of little importance, but species-specific responses to herbivory-conditioned litter can occur. Taken collectively, the overall role of the plant-litter-soil feedbackpathway, as well as its interaction with insect herbivory, is unlikely to affect broader ecosystem processes in this system.

研究背景 昆虫植食作用（insect herbivory）可影响植物生长、养分与次生代谢物含量及凋落物（litter）品质。由昆虫植食作用引发的凋落物品质变化可改变分解过程，并通过植物-凋落物-土壤反馈通路（plant-litter-soil feedback pathway）对植物生长产生连锁效应。
方法 本研究采用多阶段温室实验，探究昆虫植食作用导致的速生与慢生草本植物地上与地下凋落物品质变化，如何影响凋落物分解土壤中受试植物（response plants）的生长表现。
结果 本研究发现，昆虫植食作用仅对凋落物品质产生微弱影响；当植物分别与速生、慢生凋落物共同培养时，未对其生长造成显著影响。整体而言，凋落物的存在会抑制植物地上与地下生物量的积累，且该抑制效应对地上部分的负面影响显著强于地下部分。但该效应整体幅度极小，根与地上部分的干重生物量分别仅损失约1.4%与3.1%。进一步分析显示，经昆虫植食作用的地上凋落物，会与受试植物种类产生交互作用，进而影响地下生长。
结论 本研究结果表明，凋落物是否源自经昆虫植食作用的植物组织，以及其与速生、慢生草本植物的交互作用，对生态过程的影响均较为有限，但植物对经植食修饰的凋落物可能存在物种特异性响应。综合来看，植物-凋落物-土壤反馈通路的整体作用，及其与昆虫植食作用的交互效应，在本研究系统中不太可能对更大范围的生态系统过程产生显著影响。