三江源植被碳利用率动态变化及其对气候响应

本文基于MODIS GPP/NPP数据估算了三江源植被碳利用率（CUE），结合气象数据和高程数据采用一元线性回归和相关分析法，探讨了2001~2017年三江源植被CUE的时空变化特征及植被CUE对气温、降水量和蒸散量变化的响应.结果表明：（1）三江源植被CUE年内3~10月表现为先增加后降低的变化趋势，其中6月植被CUE最高.（2）三江源年植被碳利用率位于0.73~1，平均水平为0.85；植被CUE空间上呈现北高南低，西高东低的分布特征.（3）整体上，三江源4~10月植被碳利用率与同期气温、降水量和蒸散量分别呈现正相关、负相关和负相关关系，降水量是影响三江源植被CUE变化的主要影响因素，气温为次要因素，蒸散量影响程度最小.

Study on spatio-temporal dynamics of vegetation carbon use efficiency and its response to climate factors in Three-River Headwaters Region

Based on MODIS Gross Primary Production (GPP)/Net Primary Production (NPP) data, the carbon utilization efficiency (CUE) of vegetation in Three-River Headwaters region was calculated. Combined with the meteorological data and elevation data, the spatiotemporal distribution characteristics of vegetation CUE were investigated from 2001 to 2017 with the linear regression method. The response of vegetation CUE to air temperature, precipitation and evapotranspiration in the study area were further analyzed by using the methods of correlation analysis. The results showed that:(1) the vegetation CUE in the Three-River Headwaters region was first increasing and then decreasing with the peak in June during the active period between March and October each year from 2001 to 2017. (2) The annual vegetation CUE in the Three-River Headwaters region was ranging between 0.73 and 1.00, with an average of 0.85. Spatially, the vegetation CUE was higher in the north and west, but lower in the south and east in the study area. (3) The vegetation CUE was found to be positively correlated with air temperature, but negatively correlated with precipitation and evapotranspiration between April and October. On an annual basis, the CUE was more sensitive to precipitation than air temperature, but least sensitive to evapotranspiration.