生态恢复背景下陕甘宁地区NPP变化及其固碳释氧价值

基于MODIS NPP(植被净初级生产力)数据,利用线性趋势法、ESDA(Exploratory Spatial Data Analysis)及固碳释氧价值模型,探讨2000-2012年生态恢复背景下陕甘宁地区NPP变化及其原因,并评估NPP变化的固碳释氧价值。结果表明:(1)2000-2012年,陕甘宁地区NPP年增长率为4.3%,总体呈现阶段性增长趋势,其中有两次持续增长期;(2)陕甘宁地区NPP受水热格局影响显著,整体呈现东南高、西北低空间分布特征,空间集聚显著,但研究期内集聚水平呈下降态势,与退耕还林还草工程由前期的局部试点向后期的全区扩散相互印证;(3)陕甘宁地区NPP增长趋势是人类活动和气候因素共同作用的结果,其中人类活动为主要驱动因素,尤其是退耕还林还草工程的实施;④生态恢复背景下,陕甘宁地区植被固碳量累计增加1.06×10⁷ t,释氧量累计增加2.7×10⁷ t,固碳释氧价值累计增加9.34×10¹⁰元。生态恢复创造效益比较明显。

The NPP Change and the Vegetation Carbon Fixation/Oxygen Release Values in Shaanxi-Gansu-Ningxia Region of China

Based on the MODIS-NPP data and the linear trend method, vegetation carbon fixation/oxygen release values assessment model, ESDA (Exploratory Spatial Data Analysis) method, we analyzed the NPP change, values of fixing carbon and releasing oxygen, and the influence factors in Shaanxi-Gansu-Ningxia Region during 2000-2012. (1)From 2000 to 2012, the NPP's growth in Shaanxi-Gansu-Ningxia Region showed periodic growth trend, and there were two sustained growth periods, and the annual growth rate was 4.3%. (2)The NPP in Shaanxi-Gansu-Ningxia Region was affected by hydrothermal pattern obviously, overall the NPP was higher in northwest than in southeast, and the agglomeration level appeared downward trend during the study period. It was related to the implementation of returning farmland to forest/grassland project in 1999-2003. (3)The growth trend of NPP was affected by human activity and climate factors. Among them, human activity was the main driver, in particular, the implementation of the returning farmland to forest/grassland project. (4)In the background of ecological restoration, the vegetation carbon fixation was cumulatively increased by 1.06×10⁷ t and the oxygen released cumulatively increased by 2.7×10⁷ t in Shaanxi-Gansu-Ningxia Region, so the returning farmland to forest/grassland project created ecological benefits significantly.