Background and aimsUnderstanding the influences of environmental variation and anthropogenic disturbance on soil respiration (RS) is critical for accurate prediction of ecosystem C uptake and release. However, surprisingly, little is known about how soil respiration and its components respond to grazing in the context of global climate change (i.e., precipitation or nitrogen deposition increase).MethodsWe conducted a field manipulative grazing experiment with water and nitrogen addition treatments in a meadow grassland on the Songnen Plain, China, and assessed the combined influences of grazing and global change factors on RS, autotrophic respiration (RA), and heterotrophic respiration (RH).ResultsCompared with the control plots, RS, RA and RH all exhibited positive responses to water or nitrogen addition in the wet year, while a similar effect occurred only for RH in the dry year. The responses of RS to precipitation regimes were dominated by both frequency and amount. However, grazing significantly inhibited both soil respiration and its components in all subplots. Further analysis demonstrated that the plant root/shoot ratio, belowground biomass and microbial biomass played dominant roles in shaping these C exchange processes.ConclusionThese findings suggest that changes in precipitation regimes, nitrogen deposition, and land utilization may significantly alter soil respiration and its component processes by affecting local carbon users (roots and soil microorganism) and carbon substrate supply in meadow steppe grasslands. The future soil carbon sequestration in the studied meadow steppe will be benefited more by the moderate grazing disturbance.

中文翻译：

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放牧、水和氮添加对草甸草原土壤呼吸及其成分的不同影响

背景和目的了解环境变化和人为干扰对土壤呼吸（RS）的影响对于准确预测生态系统碳吸收和释放至关重要。然而，令人惊讶的是，在全球气候变化（即降水或氮沉积增加）的背景下，土壤呼吸及其成分对放牧的反应知之甚少。松嫩平原草地，并评估放牧和全球变化因素对 RS、自养呼吸 (RA) 和异养呼吸 (RH) 的综合影响。 结果与对照样地相比，RS、RA 和 RH 均表现出正响应在潮湿的年份添加水或氮，而类似的影响只发生在干旱年份的 RH。RS 对降水状况的响应主要受频率和数量的影响。然而，放牧显着抑制了所有子地块的土壤呼吸及其成分。进一步的分析表明，植物根/茎比、地下生物量和微生物生物量在塑造这些碳交换过程中起主导作用。结论这些发现表明降水制度、氮沉降和土地利用的变化可能显着改变土壤呼吸及其组成过程通过影响草甸草原草原的当地碳使用者（根和土壤微生物）和碳底物供应。中度放牧干扰对未来研究的草甸草原土壤固碳作用更大。