气候变化和土地利用覆盖变化对河西地区植被净初级生产力的影响

Impacts of climate change and land use/cover change on the net primary productivity of vegetation in Hexi Region,Northwest China

河西地区不仅是我国重要的生态安全保护优先区,而且是丝绸之路经济带核心地段,开展该地区植被净初级生产力(NPP)评估及驱动力定量分析对于陆地生态系统与大气碳交换、气候变化与人类活动对植被综合作用等研究具有重要的理论价值和现实意义。基于MOD17A3产品数据、土地利用覆盖数据和气象数据,采用R-贡献率和偏相关分析方法,分析了2000—2020年河西地区植被NPP变化特征及土地利用覆被和气候变化对NPP的影响,结果表明:(1)河西地区耕地、水域和居民建筑用地面积整体呈增加趋势,而草地和未利用土地面积有所减少,且2010年后的土地利用覆盖变化(LUCC)整体动态度显著提高,其中,草地、耕地、建设用地和未利用地主导了土地利用类型的相互转换。(2)河西地区整体植被NPP呈增长趋势,2000—2010年和2010—2020年的变化斜率分别为0.86和1.29,且植被NPP具有明显的区域异质性,由东南向西北递减。(3)2000—2020年河西地区LUCC对植被NPP的影响逐渐增大,且气候变化对植被NPP的贡献率普遍高于LUCC,但二者对不同土地利用覆盖类型所起的作用不同,表现为耕地、林地和草地的植被NPP影响因子以气候变化为主导,未利用土地和居民建筑用地的植被NPP影响因子逐步以LUCC为主导。

The Hexi Region holds a dual significance in China,being both a pivotal area for ecological security and the core of the Silk Road Economic Belt.The assessment of the net primary productivity(NPP)of the region and a quantitative analysis of the driving forces behind these dynamics bears immense theoretical importance and practical implications.Based on MOD17A3 product,land use cover,and meteorological information,this study scrutinized the evolving characteristics of the vegetation-related NPP,the influence of land use cover changes,and climate fluctuations on the NPP of the Hexi Region from 2000 to 2020.This study employed R-contribution rate and biased correlation analysis methods.The results show that:(1)There was an overall increase in the area of arable land,waters,and residential land in the Hexi Region,while the grassland and unused land area was reduced.The overall dynamics of land use cover change(LUCC)after 2010 was significantly higher,with grassland,cropland,built-up land,and unused land dominating the inter-conversion of land use types.(2)The overall NPP in the Hexi Region increased,with rates of change of 0.86 and 1.29 in the periods 2000-2010 and 2010-2020,respectively.There was a significant regional variation in NPP,which decreased from southeast to northwest.(3)The influence of LUCC on NPP gradually increased from 2000 to 2020.While climate change contributed more to NPP than LUCC,their respective roles varied among land use cover types.Specifically,climate change dominated the influence factor of NPP on cropland,forested land,and grassland,whereas for unutilized land and residential construction areas,LUCC played a more significant role.