青藏高原高寒湿地生态系统碳水通量与水分利用效率研究

Study on Carbon-Water Flux and Water Use Efficiency of Alpine Wetland Ecosystem in Qinghai-Tibet Plateau

为明晰高寒湿地生态系统碳水耦合机制,本研究基于2004—2009连续6年青海海北高寒湿地生态系统通量数据计算出总初级生产力和蒸散量变化,进而计算出高寒湿地水分利用效率变化。结果表明:年际尺度上,湿地生态系统呼吸速率、水分利用效率和生态系统CO_(2)净交换量均呈极显著上升趋势;季节尺度上,连续6年间非生长季生态系统碳排放总量大于生长季碳吸收总量;针对生态系统呼吸速率和水分利用效率均呈现出生长季值大于非生长季值;结构方程模型结果揭示相对湿度极显著影响高寒草甸湿地生态系统CO_(2)净交换量、生态系统呼吸速率和水分利用效率变化;水分利用效率和生态系统CO_(2)净交换量分别受净辐射和降水量的极显著影响。该研究结果可为高寒生态系统碳水耦合及对气象因子变化适应等提供理论依据。

In order to clarify the carbon-water coupling mechanism of the alpine wetland ecosystem,our study calculated the changes in total primary productivity and evapotranspiration based on the flux data of the Haibei alpine wetland ecosystem in Qinghai for six consecutive years from 2004 to 2009,and then further the changes in the water use efficiency of the alpine wetland.Our research found that:Wetland ecosystem respiration rate,water use efficiency,and ecosystem net exchange of CO_(2) all showed a significant upward trend on the interannual scale.The total amount of carbon emissions from ecosystems in the non-growing season was greater than the total amount of carbon uptake in the growing season for six consecutive years on a seasonal scale.Regarding the ecosystem respiration rate and water use efficiency,the value of the growing season was greater than the value of the non-growing season.The results of the structural equation model reveal that the relative humidity significantly affected the changes in the net CO_(2) exchange,ecosystem respiration rate,and water use efficiency of the alpine meadow wetland ecosystem.Water use efficiency and the net exchange of CO_(2) in the ecosystem were significantly affected by net radiation and precipitation,respectively.The results of our study can provide a theoretical basis for the carbon-water coupling of the alpine ecosystem and the adaptation to changes in meteorological factors.