典型干旱区植被净初级生产力的变化特征与气候因子的相关性

Variation Characteristics and Climatic Factors of Vegetation NPP in Typical Arid Region

以新疆地区为研究区,运用分辨率为1 km×1 km的MODIS遥感影像的植被指数数据,计算像元的净初级生产力(NPP)与降水、温度的偏相关系数,并借助Hurst指数对研究区植被净初级生产力未来趋势进行定量分析。结果表明:(1)植被净初级生产力1985—1998年处于高位震荡,1999—2008年呈持续下降趋势,2009—2016年基本上保持上升趋势;1985—2016年植被净初级生产力减少了67 g·m^(-2)·a^(-1),平均植被净初级生产力为154.71 g·m^(-2)·a^(-1),最大值出现在1987年(176.3 g·m^(-2)·a^(-1)),最低值出现在2008年(120.87 g·m^(-2)·a^(-1));植被净初级生产力的季节变化速率由大到小的顺序为夏季、春季、秋季。(2)年降水量与植被净初级生产力极显著正相关(P<0.01),气温与植被净初级生产力极显著负相关(P<0.01),降水量和气温的空间布局是影响植被净初级生产力分布的重要控制因素;春季和秋季植被净初级生产力与气温、降水的偏相关系数较为一致,降水为夏季植被净初级生产力的主要气候驱动因子。(3)新疆地区未来植被净初级生产力反持续性的序列的比例为48.07%,持续性的序列的比例为51.93%,因此,新疆地区未来植被净初级生产力变化以持续性减少趋势为主。

In Xinjiang, by using the MODIS remote sensing image vegetation index data with a resolution of 1 km×1 km, the partial correlation coefficient between the pixel’s net primary productivity(NPP) and precipitation and temperature was calculated, and the Hurst index was used for mathematical statistics method the future trend of vegetation NPP in the study area was quantitatively analyzed. The results show that:(1)From 1985 to 2016, the vegetation NPP fluctuated at a high level before 1998, but showed a continuous downward trend from 1999 to 2008, and basically maintained an upward trend after 2008. The vegetation NPP decreased by 67 g·m^(-2)·a^(-1). The average annual NPP in 31 years was about 154.71 g·m^(-2)·a^(-1), the highest value appeared in 1987(176.3 g·m^(-2)·a^(-1)), the lowest value appeared in 2008(120.87 g·m^(-2)·a^(-1)), the seasonal change rate of vegetation NPP in descending order of summer, spring, and autumn.(2)Taking the year as the unit of time, the precipitation and vegetation NPP mainly showed a very significantly positive correlation(P<0.01), and the temperature and vegetation NPP mainly showed a very significant negative correlation(P<0.01), precipitation and temperature space layout is an important control factor affecting the NPP distribution of vegetation. The partial correlation coefficients of vegetation NPP in spring and autumn are consistent with temperature and precipitation, and precipitation is the main climate driving factor for vegetation NPP in summer.(3)In Xinjiang, the future vegetation net primary productivity anti-persistence sequence accounted for 48.07%, and the persistence sequence accounted for 51.93%. Therefore, in the future, the change in the net primary productivity of vegetation will be dominated by a continuous decreasing trend.