The melting of permafrost and the degradation of alpine meadow ecosystems caused by climate warming and high-intensity human activities have imposed serious threats to local and global ecological security. In order to estimate the effects of climate warming and grazing interference on the photosynthesis and respiration of alpine meadow plant community in permafrost regions, warming – infrared radiator is applied to simulate the climate warming (increasing temperature by +2°С). The winter grazing level is simulated by mowing the aboveground biomass of all plants. The responses of permafrost meadow community in terms of photosynthesis, respiration, surface soil temperature and moisture, as well as the carbon balance to simulated different climate warming and grazing level were analyzed and discussed. The results showed that: (1) the surface soil temperature in climate warming and grazing plots is significantly higher than in Ck plots (P < 0.01); (2) warming and warming + grazing plots enhanced community photosynthesis and respiration (P < 0.01); (3) warming and warming + grazing treatments increased community aboveground biomass (P < 0.05); (4) the photosynthetic rate increased in the second year, then decreased in the third year when both temperature and grazing level increased during the growing season. However, the ecosystem respiration increasingly increased year by year; (5) compared with the control groups, warming and grazing treatments resulted in an increase in carbon sequestration of the permafrost meadow community during the growing season.

中文翻译：

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模拟气候变暖和放牧对多年冻土草甸植物群落光合作用和呼吸作用的影响

气候变暖和高强度人类活动导致多年冻土融化和高寒草甸生态系统退化，对当地和全球生态安全构成严重威胁。为了估计气候变暖和放牧干扰对多年冻土地区高寒草甸植物群落光合作用和呼吸作用的影响，应用变暖-红外辐射器模拟气候变暖（温度升高+2°С）。通过修剪所有植物的地上生物量来模拟冬季放牧水平。分析讨论了多年冻土草甸群落在光合作用、呼吸作用、地表土壤温度和水分以及碳平衡方面对模拟不同气候变暖和放牧水平的响应。结果表明：(1)气候变暖放牧地块表层土壤温度显着高于Ck地块(P < 0.01)；(2)增温加暖+放牧地块增强了群落光合作用和呼吸作用(P < 0.01)；(3)增温和增温+放牧处理增加了群落地上生物量（P < 0.05）；(4)随着生长季节温度和放牧水平的增加，光合速率在第二年增加，然后在第三年下降。但是，生态系统的呼吸作用逐年增加；(5) 与对照组相比，加温放牧处理导致生长季多年冻土草甸群落固碳量增加。(2)增温加暖+放牧地块增强了群落光合作用和呼吸作用(P < 0.01)；(3)增温和增温+放牧处理增加了群落地上生物量（P < 0.05）；(4)随着生长季节温度和放牧水平的增加，光合速率在第二年增加，然后在第三年下降。但是，生态系统的呼吸作用逐年增加；(5) 与对照组相比，加温放牧处理导致生长季多年冻土草甸群落固碳量增加。(2)增温加暖+放牧地块增强了群落光合作用和呼吸作用(P < 0.01)；(3)增温和增温+放牧处理增加了群落地上生物量（P < 0.05）；(4)随着生长季节温度和放牧水平的增加，光合速率在第二年增加，然后在第三年下降。但是，生态系统的呼吸作用逐年增加；(5) 与对照组相比，加温放牧处理导致生长季多年冻土草甸群落固碳量增加。(4)随着生长季节温度和放牧水平的增加，光合速率在第二年增加，然后在第三年下降。但是，生态系统的呼吸作用逐年增加；(5) 与对照组相比，加温放牧处理导致生长季多年冻土草甸群落固碳量增加。(4)随着生长季节温度和放牧水平的增加，光合速率在第二年增加，然后在第三年下降。但是，生态系统的呼吸作用逐年增加；(5) 与对照组相比，加温放牧处理导致生长季多年冻土草甸群落固碳量增加。