文献类型： 外文期刊

作者： Wen, Chao ¹ ; Shan, Yumei ² ; Xing, Tingting ³ ; Liu, Li ⁴ ; Yin, Guomei ² ; Ye, Ruhan ² ; Liu, Xinchao ² ; Chang, Hong ² ; Yi, Fengyan ² ; Liu, Sibo ¹ ; Zhang, Pujin ² ; Huang, Jianhui ⁵ ; Baoyin, Taogetao ¹ ;

作者机构： 1.Inner Mongolia Univ, Sch Ecol & Environm, Hohhot 010021, Peoples R China

2.Inner Mongolia Acad Agr & Anim Husb Sci, Hohhot 010031, Peoples R China

3.Chinese Acad Agr Sci, Inst Grassland Res, Hohhot 010010, Peoples R China

4.Inner Mongolia Hohhot City Garden Construct Serv C, Hohhot 010031, Peoples R China

5.Chinese Acad Sci, Inst Bot, State Key Lab Vegetat & Environm Change, Beijing 100093, Peoples R China

关键词： Desert steppe; Ecosystem CO2 fluxes; Precipitation increase; Nitrogen addition

期刊名称：GLOBAL ECOLOGY AND CONSERVATION （ 影响因子：4.0； 五年影响因子：4.3 ）

ISSN：

年卷期： 2024 年 52 卷

页码：

收录情况： SCI

摘要： Changes in global precipitation patterns and increased nitrogen (N) deposition have important effects on the dynamics of the carbon (C) cycle in grassland ecosystems. Long-term overgrazing caused heavy degradation of grasslands and more than 60 % of China's natural grasslands experienced moderate to severe degradation. To elucidate the effects of increasing precipitation and N deposition on C fluxes in a desert steppe ecosystem, experiments with nitrogen and water addition were conducted with four treatments, i.e., control (CK), N addition (N), water addition (W), combined addition of N and water (NW), in a Stipa breviflora desert steppe that had been heavily degraded. The ecosystem CO2 fluxes, including gross ecosystem productivity (GEP), net ecosystem CO2 exchange (NEE), and ecosystem respiration (ER), were determined using the closed chamber method during the growing seasons (May-October) of 2019 and 2020. Our results showed that water and nitrogen addition did not change the patterns of the seasonal dynamics of the ecosystem CO2 fluxes, indicating that water is the main limiting factor of CO2 fluxes in the studied desert steppe ecosystem. Precipitation increase (both W and NW treatments) stimulated all three components of the ecosystem CO2 fluxes, but N addition alone enhanced NEE and GEP while had no significant effects on ER, indicating water-induced increase of GEP was caused by both NEE and ER while N-induced increase of GEP was mainly caused by increases of NEE. Water addition can increase the effectiveness of N addition, but there was little interaction between the two factors. Soil moisture was more significantly correlated than soil temperature with ecosystem CO2 fluxes, and water addition could further enhance the correlation of ecosystem CO2 fluxes with soil temperature and moisture. Overall, ecosystem CO2 fluxes are more sensitive to the precipitation increase than to the N addition. These findings indicate that water supply will play more important role in ecosystem productivity of the desert steppe under the predicted scenarios of precipitation increase and increasing N deposition, which also provides scientific evidence for the restoration of those degraded desert steppe induced by overgrazing can not be achieved simply by increasing soil N availability.