The State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems of Lanzhou University, National Field Scientific Observation and Research Station of Grassland Agro-Ecosystems in Gansu Qingyang, College of Pastoral Agriculture Science and Technology, Lanzhou, 730020, China.
Department of Civil Engineering, Faculty of Engineering University of Peradeniya, Peradeniya, 20400, Sri Lanka.
J Environ Manage. 2022 Dec 15;324:116391. doi: 10.1016/j.jenvman.2022.116391. Epub 2022 Oct 2.
The increased frequency of extreme weather variations worldwide has resulted in dramatic changes in the soil water content via pronounced drying and rewetting cycles (DWCs). A comprehensive exploration of carbon dioxide (CO) and nitrous oxide (NO) emissions in response to DWCs can help summarize the existing results and better estimate terrestrial greenhouse gas emissions under the intensified drought and precipitation variations. This meta-analysis based on soil emissions of CO (868 observations, 29 studies) and NO (52 observations, 19 studies) at the global scale investigated the direction and intensity of the changes in soil CO and NO emissions in response to DWCs as controlled by experimental variables including land use type, soil texture, soil nutrients, and frequency and duration of DWCs. The results showed that, compared to the constant soil water content, DWCs led to the increase in CO emissions by 35.7% (95% confidence intervals ranging from 0.300 to 0.415), whereas it had no significant effect on NO emissions (-0.2638 to 1.4751). The random-effects model indicated that soil water-filled pore space during wetting, soil clay content, days of drying and wetting, and frequency of DWCs significantly affected CO and NO emissions in response to DWCs. Furthermore, potential biotic and abiotic factors affecting soil CO and NO emissions under DWCs are also summarized, and it was proposed that mobility and availability of carbon substrate as well as enhanced microbial activity and abundance are the main drivers facilitating soil CO and NO emissions in response to DWCs. However, soil gas diffusion or oxygen availability also dominated soil NO emissions under DWCs. Overall, this study improves our understanding of soil CO and NO emissions in response to various DWC scenarios and facilitates the development of better greenhouse gas mitigation strategies against the background of a rapidly changing climate.
全球极端天气变化频率的增加导致土壤含水量通过明显的干燥和再湿润循环（DWCs）发生剧烈变化。全面探讨二氧化碳（CO）和氧化亚氮（NO）排放对 DWCs 的响应，可以帮助总结现有结果，并更好地估计在加剧的干旱和降水变化下陆地温室气体排放。本研究基于全球范围内土壤 CO（868 个观测值，29 项研究）和 NO（52 个观测值，19 项研究）排放的元分析，研究了实验变量（包括土地利用类型、土壤质地、土壤养分以及 DWCs 的频率和持续时间）控制下 DWCs 对土壤 CO 和 NO 排放变化的方向和强度。结果表明，与恒定的土壤含水量相比，DWCs 导致 CO 排放增加了 35.7%（95%置信区间为 0.300 至 0.415），而对 NO 排放没有显著影响（-0.2638 至 1.4751）。随机效应模型表明，湿润时土壤水填充的孔隙空间、土壤粘粒含量、干燥和湿润天数以及 DWCs 的频率均显著影响 CO 和 NO 排放对 DWCs 的响应。此外，还总结了影响 DWCs 下土壤 CO 和 NO 排放的潜在生物和非生物因素，并提出了促进 DWCs 下土壤 CO 和 NO 排放的主要驱动力是碳底物的迁移性和可用性以及增强的微生物活性和丰度。然而，在 DWCs 下土壤气体扩散或氧气可用性也主导了土壤 NO 排放。总的来说，本研究提高了我们对不同 DWCS 情景下土壤 CO 和 NO 排放的理解，并有助于在快速变化的气候背景下制定更好的温室气体减排策略。
