【摘要】 建植多年生人工草地已成为生态环境保护和恢复工程的重要措施之一,探究多年生人工草地生态系统CO₂交换的变化特性,有助于准确评估和预测人工草地碳收支状况及其生态服务功能。利用2012-2016年,5年的涡度相关系统观测的数据,分析了三江源农牧交错区垂穗披碱草（Elymus nutans）人工草地的净生态系统CO₂交换（Net ecosystem CO₂ exchange,NEE）、总初级生产力（Gross primary productivity,GPP）和生态系统呼吸（Ecosystem respiration,R）等参数在一个种植周期的变化特征及其控制因子。结果表明:（1）在一个完整种植周期内（5年）,三江源农牧交错区垂穗披碱草人工草地随着种植年限的增加CO₂通量先增加后减小,累计固碳180.4 g·m^-2,是一个弱的碳汇,其中,除了种植第1年表现为碳源(47g·m^-2),其他年份均为碳汇,第3年碳汇强度达到最强-128.3 g·m^-2;（2）GPP主要由空气温度、植被多样性指数（Simpson指数）和生长季长度共同控制（r²=0.92）,植被多样性指数（Simpson指数）直接影响着生长季NEE（r²=0.80）;（3）管理措施（播种和收割时间）影响着生长季的长度,而生长季长度影响非生长季R和生长季NEE的比值（R/NEE）（96%）,进而影响着NEE的年际变异（92%）,管理措施影响着人工草地NEE的年际变异。不论是生产功能还是生态功能,每5-6年重新翻耕人工草地是"生产-生态"的双赢模式,人工草地更新是三江源农牧交错区一个生产和生态相结合的有效产业发展模式。更多还原

【Abstract】 Development of artificial grassland has become one of the important elements of the ecological environmental protection and restoration project.Understanding the dynamics of CO₂ exchange is required for accurately predicting and evaluating the carbon budget and ecological service function of the perennial artificial grassland ecosystem.In this study,we analyzed 5 years datas（2012-2016）from eddy covariance observations of an Elymus nutans grassland in agro-pastoral transition area of Sanjiangyuan to identify the features and decisive factors of net ecosystem CO₂ exchange（NEE）,gross primary productivity（GPP）,ecosystem respiration（R）.The results showed that,（1）in a complete planting cycle（5 years）,the CO₂ flux was increased then decreased with the increase of the plant years.The total cumulative CO₂ uptake was 180.4 g·m^-2（by C）during the production cycle,indicating that the studied grassland was a weak C sink.Further analysis showed that,the studied artificial grassland was a carbon source in the first planting year and contributed 47 g·m^-2 C.From year 2 to 5,the grassland served as carbon sinks and in the 3rd year carbon sink strength reached the strongest at-128.52 g·m^-2·a^-1.（2）GPP in growing season was mainly controlled by air temperature,Simpson index and length of growing season（r²=0.92）.A clear linear relationship between NEE and Simpson index was evident in growing seasons（r²=0.80）.And（3）management（seeding and harvesting time）affected the length of the growing season,while the growth season length impacted the ratio of R to the growing season NEE（R/NEE）（96%）.The length of the growing season also affected the R/NEE ratio of the non-growing season by directly determining the interannual variability of NEE（92%）.In addition,management affected the interannual variability of NEE.Together,the present study reveals that re-planting grassland every 5-6 years is a win-win system of"production-ecology",regardless of carbon sequestration function or production function.Developing artificial grassland is an effective way to balance ecology and production in agro-pastoral transition area of Sanjiangyuan.更多还原