Moderate precipitation reduction enhances nitrogen cycling and soil nitrous oxide emissions in a semi-arid grassland |
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Authors: | Kangcheng Zhang Yunpeng Qiu Yunfeng Zhao Shuhong Wang Jun Deng Mengfei Chen Xinyu Xu Hao Wang Tongshuo Bai Tangqing He Yi Zhang Huaihai Chen Yi Wang Shuijin Hu |
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Institution: | 1. College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095 China;2. Ningxia Yunwu Mountains Grassland Natural Reserve Administration, Guyuan, 756000 China;3. School of Ecology, Sun Yat-Sen University, Guangzhou, 510006 China;4. State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, China;5. Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, North Carolina, 27695 USA |
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Abstract: | The ongoing climate change is predicted to induce more weather extremes such as frequent drought and high-intensity precipitation events, causing more severe drying-rewetting cycles in soil. However, it remains largely unknown how these changes will affect soil nitrogen (N)-cycling microbes and the emissions of potent greenhouse gas nitrous oxide (N2O). Utilizing a field precipitation manipulation in a semi-arid grassland on the Loess Plateau, we examined how precipitation reduction (ca. ?30%) influenced soil N2O and carbon dioxide (CO2) emissions in field, and in a complementary lab-incubation with simulated drying-rewetting cycles. Results obtained showed that precipitation reduction stimulated plant root turnover and N-cycling processes, enhancing soil N2O and CO2 emissions in field, particularly after each rainfall event. Also, high-resolution isotopic analyses revealed that field soil N2O emissions primarily originated from nitrification process. The incubation experiment further showed that in field soils under precipitation reduction, drying-rewetting stimulated N mineralization and ammonia-oxidizing bacteria in favor of genera Nitrosospira and Nitrosovibrio, increasing nitrification and N2O emissions. These findings suggest that moderate precipitation reduction, accompanied with changes in drying-rewetting cycles under future precipitation scenarios, may enhance N cycling processes and soil N2O emissions in semi-arid ecosystems, feeding positively back to the ongoing climate change. |
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Keywords: | legacy effect N-cycling microorganisms precipitation reduction semi-arid ecosystems soil nitrous oxide emissions |
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