Liu Yuwei, Zou Xiaoming, Chen Han Y H, Delgado-Baquerizo Manuel, Wang Cuiting, Zhang Chen, Ruan Honghua
Department of Ecology, Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, China.
Department of Environmental Science, College of Natural Sciences, University of Puerto Rico, San Juan, Puerto Rico, USA.
Glob Chang Biol. 2023 Dec;29(24):7159-7172. doi: 10.1111/gcb.16978. Epub 2023 Oct 13.
The frequency and intensity of droughts worldwide are challenging the conservation of soil organic carbon (SOC) pool. Microbial necromass is a key component of SOC, but how it responds to drought at specific soil depths remains largely unknown. Here, we conducted a 3-year field experiment in a forest plantation to investigate the impacts of drought intensities under three treatments (ambient control [CK], moderate drought [30% throughfall removal], and intensive drought [50% throughfall removal]) on soil microbial necromass pools (i.e., bacterial necromass carbon, fungal necromass carbon, and total microbial necromass carbon). We showed that the effects of drought on microbial necromass depended on microbial groups, soil depth, and drought intensity. While moderate drought increased total (+9.1% ± 3.3%) and fungal (+13.5% ± 4.9%) necromass carbon in the topsoil layer (0-15 cm), intensive drought reduced total (-31.6% ± 3.7%) and fungal (-43.6% ± 4.0%) necromass in the subsoil layer (15-30 cm). In contrast, both drought treatments significantly increased the BNC in the topsoil and subsoil. Our results suggested that the effects of drought on the microbial necromass of the subsoil were more pronounced than those of the topsoil. This study highlights the complex responses of microbial necromass to drought events depending on microbial community structure, drought intensity and soil depth with global implications when forecasting carbon cycling under climate change.
全球干旱的频率和强度正对土壤有机碳（SOC）库的保护构成挑战。微生物残体是土壤有机碳的关键组成部分，但在特定土壤深度下其对干旱的响应仍 largely unknown。在此，我们在一个人工林中进行了为期 3 年的田间试验，以研究三种处理（对照 [CK]、中度干旱 [去除 30% 的穿透水] 和重度干旱 [去除 50% 的穿透水]）下干旱强度对土壤微生物残体库（即细菌残体碳、真菌残体碳和总微生物残体碳）的影响。我们发现，干旱对微生物残体的影响取决于微生物类群、土壤深度和干旱强度。虽然中度干旱使表层土壤（0 - 15 厘米）中的总残体碳（+9.1% ± 3.3%）和真菌残体碳（+13.5% ± 4.9%）增加，但重度干旱使下层土壤（15 - 30 厘米）中的总残体碳（-31.6% ± 3.7%）和真菌残体碳（-43.6% ± 4.0%）减少。相比之下，两种干旱处理均显著增加了表层土壤和下层土壤中的细菌残体碳。我们的结果表明，干旱对下层土壤微生物残体的影响比对表层土壤更为显著。这项研究突出了微生物残体对干旱事件的复杂响应，这取决于微生物群落结构、干旱强度和土壤深度，在预测气候变化下的碳循环时具有全球意义。
