As a cause of ecosystem disturbances, phytophagous insects are known to directly influence the element and organic matter (OM) cycling in ecosystems by their defoliation and excretion activity. This study focuses on the interplay between short‐term, insect herbivory, plant responses to feeding activity, rhizosphere processes, and belowground nutrient availability under nutrient‐poor soil conditions. To test the effects of insect herbivory on OM and nutrient cycling in an N‐limited pasture system, mesocosm laboratory experiments were conducted using Dactylis glomerata as common grass species and Chorthippus dorsatus, a widespread grasshopper species, to induce strong defoliating herbivory. ¹³CO₂ pulse labeling was used together with labeled ¹⁵N feces to trace the fate of C in soil respiration at the beginning of herbivory, and of C and N in above‐ and belowground plant biomass, grasshopper, feces, bulk soil, soil microbial biomass, throughfall solutions, and soil solutions. Within five days, herbivory caused a reduction in aboveground grass biomass by about 34%. A linear mixed‐effects model revealed that herbivory significantly increased total dissolved C and N amounts in throughfall solutions by a factor of 4–10 (P < 0.05) compared with the control. In total, 27.6% of the initially applied feces ¹⁵N were translocated from the aboveground to the belowground system. A significant enrichment of ¹⁵N in roots led to the assumption that feces‐derived ¹⁵N was rapidly taken up to compensate for the frass‐related foliar N losses in light of N shortage. Soil microorganisms incorporated newly available ¹³C; however, the total amount of soil microbial biomass remained unaffected, while the exploitative grass species rapidly sequestered resources to facilitate its regrowth after herbivory attack. Heavy herbivory by insects infesting D. glomerata‐dominated, N‐deficient grasslands remarkably impacted belowground nutrient cycling by an instant amplification of available nutrients, which led to an intensified nutrient competition between plants and soil microorganisms. Consequently, these competitive plant–soil microbe interactions accelerated N cycling and effectively retained herbivory‐mediated C and N surplus release resulting in diminished N losses from the system. The study highlighted the overarching role of plant adaptations to in situ soil fertility in short‐term ecosystem disturbances.

中文翻译：

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限草系统中的蚱hopper食草立即影响元素循环，但不影响出口率

吞噬食性昆虫是导致生态系统紊乱的原因，其脱叶和排泄活动直接影响生态系统中的元素和有机质（OM）循环。这项研究的重点是在营养贫瘠的土壤条件下，短期食草动物，植物对摄食活动的反应，根际过程和地下养分有效性之间的相互作用。为了测试在N限制牧场系统中食草动物对OM和养分循环的影响，我们使用小球藻（Dactylis glomerata）作为常见草种和广or蝗（Chorthippus dorsatus）进行了中观实验室实验，以诱导强烈的落叶性草食动物。¹³一氧化碳₂脉冲标记与标记的¹⁵ N粪便一起使用，以追踪食草开始时土壤呼吸中C的命运，以及地下和地下植物生物量，蚱hopper，粪便，散装土壤，土壤微生物量，通透性中C和N的命运溶液和土壤溶液。在五天内，食草导致地上草的生物量减少了约34％。线性混合效应模型显示，与对照相比，食草动物显着增加了穿透溶液中总溶解碳和氮的含量，为4-10倍（P  <0.05）。总共有27.6％的最初使用的粪便¹⁵ N从地上系统转移到地下系统。丰富的¹⁵根系中的氮导致这样的假设，即由于氮的缺乏，粪便中的¹⁵ N被迅速吸收以补偿与草相关的叶面N的损失。掺入了新近获得的土壤微生物的¹³ C; 然而，土壤微生物生物量的总量并未受到影响，而在草食性攻击后，可利用的草种迅速隔离了资源以促进其再生。昆虫侵染D. glomerata的大量草食动物氮不足的占主导地位的草原通过迅速放大可用养分而显着影响地下养分循环，从而导致植物与土壤微生物之间的养分竞争加剧。因此，这些竞争性的植物-土壤微生物相互作用加快了氮的循环并有效地保留了草食性介导的碳和氮的过量释放，从而减少了系统中氮的损失。该研究强调了在短期生态系统扰动中，植物适应对土壤原位肥力的总体作用。