Legesse Tsegaye Gemechu, Qu Luping, Dong Gang, Dong Xiaobing, Ge Tida, Daba Nano Alemu, Tadesse Kiya Adare, Sorecha Eba Muluneh, Tong Qi, Yan Yuchun, Chen Baorui, Xin Xiaoping, Changliang Shao
National Hulunbuir Grassland Ecosystem Observation and Research Station & Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Forest Ecology Stable Isotope Center, Forestry College, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
Sci Total Environ. 2022 Dec 10;851(Pt 1):158130. doi: 10.1016/j.scitotenv.2022.158130. Epub 2022 Aug 20.
The imbalance of terrestrial carbon (C) inputs versus losses to extreme precipitation can have consequences for ecosystem carbon balances. However, the current understanding of how ecosystem processes will respond to predicted extreme dry and wet years is limited. The current study was conducted for three years field experiment to examine the effects of environmental variables and soil microbes on soil respiration (Rs), autotrophic respiration (Ra) and heterotrophic respiration (Rh) under extreme wet and dry conditions in mowed and unmowed grassland of Inner Mongolia. Across treatments (i.e. control, dry spring, wet spring, dry summer and wet summer), the mean of Rs was increased by 24.9 % and 24.1 % in the wet spring and wet summer precipitation treatments, respectively in mowed grassland. In other hand, the mean of Rs was decreased by -22.1 % and -3.5 % in dry spring and dry summer precipitation treatments, respectively in mowed grassland. The relative contribution of Rh and Ra to Rs showed a significant (p < 0.05) change among simulated precipitation treatments with the highest value (76.18 %) in wet summer and 26.41 % in dry summer, respectively under mowed grassland. Rs was significantly (p < 0.05) affected by the interactive effect of extreme precipitation and mowing treatments in 2020 and 2021. The effects of precipitation change via these biotic and abiotic factors explained by 52 % and 81 % in Ra and Rh, respectively in mowed grassland. The changes in microbial biomass carbon (MBC) and nitrogen (MBN) had significant (p < 0.05) direct effects on Rh in both mowed and unmowed grasslands. The influence of biotic and abiotic factors on Rs was stronger in mowed grasslands with higher standardized regression weights than in unmowed grassland (0.78 vs. 0.69). These findings highlight the importance of incorporating extreme precipitation events and mowing in regulating the responses of C cycling to global change in the semiarid Eurasian meadow steppe.
陆地碳（C）输入与极端降水造成的损失之间的不平衡可能会对生态系统碳平衡产生影响。然而，目前对于生态系统过程将如何应对预测的极端干旱和湿润年份的理解仍然有限。本研究通过为期三年的田间试验，考察了内蒙古割草和未割草草地下极端湿润和干旱条件下环境变量和土壤微生物对土壤呼吸（Rs）、自养呼吸（Ra）和异养呼吸（Rh）的影响。在各处理（即对照、春季干旱、春季湿润、夏季干旱和夏季湿润）中，割草草地下春季湿润和夏季湿润降水处理的Rs平均值分别增加了24.9%和24.1%。另一方面，割草草地下春季干旱和夏季干旱降水处理的Rs平均值分别下降了-22.1%和-3.5%。在割草草地下，Rh和Ra对Rs的相对贡献在模拟降水处理之间呈现出显著（p < 0.05）变化，夏季湿润时最高值为76.18%，夏季干旱时为26.41%。2020年和2021年，Rs受到极端降水和割草处理交互作用的显著（p < 0.05）影响。在割草草地下，通过这些生物和非生物因素导致的降水变化分别解释了Ra和Rh中52%和81%的变化。微生物生物量碳（MBC）和氮（MBN）的变化在割草和未割草草地下均对Rh有显著（p < 0.05）直接影响。与未割草地相比，割草草地下生物和非生物因素对Rs的影响更强，标准化回归权重更高（0.78对0.69）。这些发现突出了纳入极端降水事件和割草在调节半干旱欧亚草甸草原碳循环对全球变化响应中的重要性。
