Effects Of Simulated Warming On Photosynthesis In Two Types Of Grassland In The Qinghai Lake Basin

Under the background of global climate change,the effect of climate change on vegetation photosynthesis has become a hot research topic.According to the analysis of the ecological types of the terrestrial ecosystem,the most important part is grassland,which has an important influence on the whole terrestrial ecosystem,is its carbon cycle system can not be ignored part.At the present stage,the global warming situation is getting more and more serious.The average annual temperature in the Qinghai Lake River basin is gradually increasing,and the degree of annual change curve is more obvious,the large-scale change of climate directly affects the photosynthesis of grassland ecosystem in the region.At this stage,based on the results of academic research and analysis,we can know that the Qinghai Lake River basin as a case study of the impact of photosynthesis on the impact of temperature rise in the literature is relatively small,based on current research in the academic field,this study was conducted to collect and collate data on photosynthesis of two types of grasslands in the middle Qinghai Lake River basin during the 2022 growing season from June to September,at the same time,based on the change degree of core environmental factors and biological factors,the comprehensive simulation of the effects of increasing temperature on photosynthesis and related mechanism of alpine meadow and temperate steppe in this basin was realized,the results of this topic can be summarized as follows:(1)the surface air temperature and soil 10 cm temperature and humidity of alpine meadow and temperate steppe increased first and then decreased.There was a significant difference between the two groups in the land surface temperature,except for the warm steppe in September(P<0.05).The difference between the control group and the alpine meadow and the warm steppe was significant,there was no significant difference between the two groups(P > 0.05).The lowest and the highest 10 cm soil temperature of alpine meadow and temperate steppe occurred in September and August respectively,and there was no significant difference between the treatment group and the control group(P > 0.05)In addition to the significant difference of 10 cm soil moisture between the warm steppe and the control in September(P<0.05),the soil moisture of the warm steppe was significantly higher than that of the control,the soil moisture of 10 cm in alpine meadow and temperate steppe did not reach significant level in other months compared with the control group(P > 0.05).(2)the aboveground biomass of alpine meadows and temperate steppe showed a single-peak trend during the whole growing season,and the total biomass reached the maximum value in August,the aboveground biomass of the alpine meadow was higher than that of the control group,the underground biomass was lower than that of the control group,and the mean aboveground biomass of the temperate grassland was lower than that of the control group,the underground biomass of temperate steppe was higher than that of the control under simulated warming.The diurnal variation trend of alpine meadow was consistent in every month of growing season,and showed a bimodal pattern in general.The mean net photosynthetic rate of alpine meadow was higher than that of the control group under the treatment of increasing temperature,the phenomenon of“Midday break” of plant photosynthesis was observed from June to August.The diurnal variation trend of the temperate steppe was the same,and the warming treatment and the control showed a single-peak variation trend.(3)the diurnal variation trend of alpine meadow was consistent in every month of growing season,and showed a bimodal pattern in general.The mean net photosynthetic rate of alpine meadow was higher than that of the control group under the treatment of increasing temperature,the phenomenon of“Midday break” of plant photosynthesis was observed from June to August.The diurnal variation trend of the temperate steppe was the same,and the warming treatment and the control showed a single-peak variation trend.In this study,the effects of warming on photosynthesis in two types of grassland were investigated.The results are important for exploring the function of carbon source/sink and predicting the dynamic change of grassland carbon under future global change.(4)the photosynthetic characteristics of alpine meadow and temperate steppe showed a single-peak curve that first increased and then decreased.The change trend of photosynthetic characteristics of alpine meadow and temperate steppe from June to September was consistent with the change trend of atmospheric temperature and photosynthetic effective radiation,the results showed that both alpine meadow and temperate steppe had positive responses to simulated warming.In this study,the effects of warming on photosynthesis in two types of grassland were investigated.The results are important for exploring the function of carbon source/sink and predicting the dynamic change of grassland carbon under future global change.