高寒湿地旱化过程及其对CO2交换的影响

为研究青藏高原高寒湿地旱化对碳通量的影响，探讨高寒湿地旱化碳通量变化规律，本研究于7-8月生长高峰期以高寒湿地、沼泽化草甸和高寒草甸为研究对象，利用TARGAS-1静态箱法，比较高寒湿地不同退化阶段碳交换的动态差异。结果表明：与高寒湿地相比，沼泽化草甸与高寒草甸植被群落光合速率、生态系统呼吸速率、净生态系统碳交换显著提高（P<0.05）；不同退化阶段土壤温湿度及植被群落生物量存在显著差异（P<0.05），土壤电导率差异不显著；相比于土壤湿度和土壤电导率，土壤温度对CO₂交换的影响更大，其与净生态系统碳交换呈显著负相关（P<0.05），高寒草甸的碳交换对土壤温度的敏感性要大于高寒湿地和沼泽化草甸的碳交换对土壤温度的敏感性；在植物生长高峰期，高寒湿地旱化过程土壤温度显著上升，土壤湿度和植物群落生物量显著下降，导致其碳汇功能呈下降趋势。

Drought Processes of Alpine Wetland and Their Influences on CO2 Exchange

Effects of drought processes of alpine wetland on carbon flux on the Qinghai-Tibetan Plateau were analyzed to discuss the changes of carbon flux during the drought processes of alpine wetland. Alpine wetland,swamp meadow and alpine meadow were selected in this study. The TARGAS-1 static box method was used to perform a carbon flux dynamic detection test so as to explore the differences of carbon exchange in the drought processes in alpine wetland at the peak of plant growth in July and August. The results showed that photosynthetic rate,ecosystem respiration rate and net ecosystem carbon exchange of vegetation community in swamp meadow and alpine meadow were significantly increased (P<0.05),compared within alpine wetland;There were significant differences in soil temperature and moisture,and vegetation community biomass at different degradation stages (P<0.05),but there was no significant difference in soil electrical conductivity;Compared with soil moisture and soil conductivity,soil temperature had the greatest effect on CO₂ exchange,and the temperature had a significantly negative relationship with net ecosystem carbon exchange (P<0.05). The carbon exchange in alpine meadow was more sensitive to soil temperature than that in alpine wetland and swamp meadow;With the drought processes of alpine wetland at the peak of plant growth,the soil temperature increased significantly,and wetland soil moisture and plant community biomass decreased. The functions of carbon sink in alpine wetland presented as a downward trend.