Drought and extreme precipitation are projected to occur more frequently as a consequence of climate change, with uncertain implications for soil CO emission. Although studies have revealed the response patterns of soil CO emission to precipitation pulse, the effects of forest plant roots on this relationship after drought are still poorly understood. Here, a field experiment was performed to examine the differences in soil CO emission and microbial community between rootless and rooted soils, pretreated with three drought intensities (control, moderate, and severe), and rewetted with different water additions (0, 5, 10, and 20 mm) in a temperate forest. Compared with control soils, whether the water was added or not, severe drought suppressed soil CO emission for both root-excluded and -included soils. Regardless of drought intensities, significantly positive effects (19.4–44.9%) of precipitation pulse on soil CO emission were only detected in the root-included soils. Both the contribution of root-derived CO to the stimulated soil CO emission and biomass of soil arbuscular mycorrhizal fungi (AMF) substantially increased with elevated precipitation levels. The enhanced soil CO emission following precipitation pulse is primarily due to the increase in root-derived CO in the rooted soils, likely resulting from the enhanced biomass of soil AMF. This study provides empirical evidence on the primacy of AMF in root-derived CO and thus the response of soil CO emission to precipitation pulse in forest ecosystems.

中文翻译：

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丛枝菌根真菌影响根系土壤干旱后土壤二氧化碳排放对夏季降水脉冲的响应


由于气候变化，干旱和极端降水预计将更加频繁地发生，这对土壤二氧化碳排放产生不确定的影响。尽管研究揭示了土壤二氧化碳排放对降水脉冲的响应模式，但干旱后森林植物根系对这种关系的影响仍知之甚少。在这里，进行了一项田间实验，以检查无根土壤和有根土壤之间土壤二氧化碳排放和微生物群落的差异，这些土壤经过三种干旱强度（对照、中度和重度）预处理，并用不同的加水量（0、5、10和 20 毫米）在温带森林中。与对照土壤相比，无论是否加水，严重干旱均抑制了排除根系土壤和包含根系土壤的土壤二氧化碳排放。无论干旱强度如何，降水脉冲对土壤二氧化碳排放的显着积极影响（19.4-44.9%）仅在含根的土壤中检测到。随着降水量的增加，根系二氧化碳对土壤二氧化碳排放的贡献和土壤丛枝菌根真菌（AMF）的生物量均大幅增加。降水脉冲后土壤二氧化碳排放量的增加主要是由于根部土壤中根部来源二氧化碳的增加，这可能是由于土壤 AMF 生物量的增加所致。本研究提供了 AMF 在根源 CO 中的首要地位以及土壤 CO 排放对森林生态系统降水脉冲的响应的经验证据。