Soil respiration (SR TOT ) and its main components, soil heterotrophic (SR H ) and autotrophic respiration (SR A ), were monitored in response to within-season drought events of increasing duration and soil N enrichment in a semiarid meadow steppe. The experiment consisted of the combination of five drought periods (0 days, 15 days, 30 days, 45 days, and 60 days) and two N addition levels (0 and 10 g N m −2 year −1 applied as urea). Soil respiration decreased after 30 days of drought, with the response being driven by soil heterotrophs. Moreover, N addition increased the sensitivity of soil respiration to soil water content, which we attributed to greater plant C inputs and soil microbial C and N content in the N addition treatment. Our results highlight the role of SR H as a key regulator of C fluxes in nutrient-poor semiarid meadow steppe in response to extreme within-season drought and the role of soil N availability in modulating this response.

中文翻译：

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草甸草原自养和异养土壤呼吸响应干旱持续时间和氮添加的非线性解耦

监测土壤呼吸（SR TOT ）及其主要成分，土壤异养呼吸（SR H ）和自养呼吸（SR A ），以响应半干旱草地草原中持续时间增加和土壤氮富集的季节内干旱事件。实验由五个干旱期（0 天、15 天、30 天、45 天和60 天）和两个氮添加水平（0 和 10 g N m -2 年 -1 用作尿素）的组合组成。土壤呼吸在干旱 30 天后下降，响应是由土壤异养生物驱动的。此外，氮添加增加了土壤呼吸对土壤含水量的敏感性，我们将其归因于氮添加处理中更大的植物碳输入和土壤微生物碳和氮含量。