2001-2010年三江源区草地净生态系统生产力估算

Net Ecosystem Production of Alpine Grasslands in the Three-River Headwaters Region during 2001-2010

三江源区位于青藏高原腹地,是我国长江、黄河、澜沧江三大河流的发源地.为了准确估算该地区草地生态系统的净生态系统生产力,收集整理了2001—2010年青藏高原10个通量观测站点的观测数据,构建了三江源区草地生态系统NEP(net ecosystem production,净生态系统生产力)估算模型,并在站点尺度进行了模型参数化和精度验证;结合区域尺度气象和遥感数据,估算了三江源区草地生态系统NEP.结果表明:12001—2010年三江源区草地生态系统多年平均NEP空间分布具有明显的空间异质性,大部分地区表现为碳汇,NEP(以C计)平均值为41.8 g/(m^2·a).2三江源区草地生态系统NEP呈波动增加趋势,从2001年的20.0 g/(m^2·a)增至2010年的82.5 g/(m^2·a);除2002年表现为弱碳源外,其余年份均表现为碳汇,并以2010年碳汇能力为最强.32001—2010年三江源区草地生态系统NEP平均年增长率为5.4 g/m^2;NEP年际变化率空间分布显示,大部分地区NEP呈增加趋势,仅有东南部和中部部分区域NEP呈下降趋势.研究显示,2001—2010年三江源区草地生态系统表现为碳汇,并且由于气候的暖湿化趋势,碳汇强度总体表现为增强.

The Three-River Headwaters Region,located on the Qinghai-Tibet Plateau,is the water source of the Yangtze River,Yellow River and Lantsang River. To accurately estimate the net ecosystem production（ NEP） of the grasslands in this region,the NEP and parameterized models were developed based on eddy covariance flux observation data collected at 10 sites on the Qinghai-Tibet Plateau.Driven by spatial meteorological and remote sensing data,the grassland NEP in the Three River Headwaters Region from 2001 to 2010 was simulated by the model. The results showed that the spatial distribution of NEP had significant spatial heterogeneity, and grasslands in most areas act as carbon sinks,with the average NEP value for all pixels being 41. 8 g/（ m^2·a）. Average grassland NEP increased during 2001-2010,rising from 20. 0 g/（ m^2·a） in2001 to 82. 5 g/（ m^2·a） in 2010. Grasslands in the Three River Headwaters Region functioned as a carbon sink from 2001 to2010,with the exception of 2002. The spatial distribution of the inter-annual variability of NEP had evident regional heterogeneity,which increased in most areas but decreased in some parts of the southeast and middle regions. Overall,the mean increasing rate of annual NEP of all pixels was 5. 4 g/m^2. These results indicated that the alpine grasslands in the Three River Headwaters Region were a carbon sink during 2001-2010,and the strength of the sink was enhancing due to the increasing temperature and precipitation.