Abstract Extracellular enzyme activities (EEA) in soils play a pivotal role in ecosystem processes, such as organic carbon (C) decomposition or nitrogen (N) and phosphorus (P) mineralization. Thus, EEA measurements can provide insights into the rates of ecosystem-level processes in peatlands, which will experience more frequent extreme droughts in the future. In the present study, the activities of seven hydrolases and two oxidases involved in the acquisition of C, N, and P were measured in response to simulated extreme drought events during the summer. The combined results of three consecutive years showed that the β-1,4-glucosidase and β-1,4-xylosidase involved in mediating labile-C decomposition increased by 102.63% and 100.63%, respectively. In contrast, the oxidases involved in mediating recalcitrant-C decomposition showed a non-significant decreasing trend, indicating that extreme drought significantly increased the decomposition of cellulose in peatlands. The C-acquisition enzyme, C:P -acquisition enzyme, and N:P-acquisition enzyme activities increased, on average, by 78.45%, 51.57%, and 36.57%, respectively, under extreme drought, impacting the rates of microbial growth and organic matter depolymerization. In addition, the results showed that changes in the C-acquisition enzyme were correlated with shifts in the soil water content, whereas soil oxidases were correlated with soil total C and N contents. Overall, the soil total C content explained 41.9% of the variation in EEA and ecoenzymatic stoichiometry. These results provide an improved understanding of hydrolase and oxidase activities in response to extreme drought events, thereby facilitating the prediction of long-term C dynamics in peatlands.

中文翻译：

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青藏高原高寒泥炭地土壤水解酶和氧化酶对极端干旱的不同响应

摘要 土壤中的细胞外酶活性 (EEA) 在生态系统过程中起着关键作用，例如有机碳 (C) 分解或氮 (N) 和磷 (P) 矿化。因此，EEA 测量可以深入了解泥炭地中生态系统水平过程的速率，泥炭地未来将经历更频繁的极端干旱。在本研究中，为响应夏季模拟的极端干旱事件，测量了参与 C、N 和 P 获取的七种水解酶和两种氧化酶的活性。连续三年的综合结果表明，参与介导不稳定C分解的β-1,4-葡萄糖苷酶和β-1,4-木糖苷酶分别增加了102.63%和100.63%。相比之下，参与介导顽固-C分解的氧化酶呈不显着下降趋势，表明极端干旱显着增加了泥炭地纤维素的分解。C-获取酶、C:P-获取酶和N:P-获取酶活性在极端干旱下平均分别增加了78.45%、51.57%和36.57%，影响了微生物的生长速度和有机物解聚。此外，结果表明，C-获取酶的变化与土壤含水量的变化相关，而土壤氧化酶与土壤总 C 和 N 含量相关。总体而言，土壤总碳含量解释了 EEA 和生态酶化学计量变化的 41.9%。