2000-2021年桂西南峰丛洼地流域植被净初级生产力演变特征及其归因OA北大核心CSTPCD

China has about 3.44× 106 km2 of karst area,and the most typical karst landscape—one of the largest in the world—is distributed in Southwest China,covering an area of 4.26×105 km2.The karst area in Southwest China has a total population of more than 100 million in 48 ethnic minorities.Meanwhile,it is the major poverty-stricken area in China,with nearly half of the country's poor population.The peak-cluster depression basin in Guangxi is located in the southwest of Guangxi Zhuang Autonomous Region,including most parts of 3 prefecture-level cities—Baise,Wenshan and Chongzuo,as well as some areas of Nanning City and Fangchenggang City.The peak-cluster depression basin in southwest Guangxi is an old revolutionary base area and autonomous region for ethnic minorities along China's land boundary.It is not only an essential ecological barrier of the Pearl river basin,but also an important area for water conservation and biodiversity protection in China.However,this peak-cluster depression basin is subject to severe rock desertification and the scarcity of vegetation,because this basin is extensively developed with karst landscape,characterized by unique double-layer hydrogeological structures and shallow soil layer with severe soil erosion.This basin falls under the zone of southern subtropical climate,which is subdivided into the central subtropical climate zone(southern Guangxi climate zone),including Fangchenggang and Nanning,and the western subtropical climate zone(southwestern Guangxi climate zone),mainly including Baise,Pingxiang and Chongzuo.Due to the unique geography and fragile ecological environment of this basin,monitoring and analyzing the evolution and driving mechanism of the net primary productivity(NPP)of vegetation plays an important role in insight into the terrestrial carbon cycle mechanism and in sustainable development of the ecological environment. This study assessed the spatial and temporal evolution of NPP in the typical karst peak-cluster depression basin in southwestern Guangxi from 2000 to 2021,based on the MOD17A3 dataset NPP products,and investigated the spatial distribution,future trends,sustainability and driving mechanisms of NPP in this region with Theil-Sen Median trend analysis,Mann-Kendall test method,Hurst index and geodetector.The results show:(1)From 2000 to 2021,the average value of NPP in the study area was 945.23 gC·m-2·a-1,with an increase rate of 3.5596 gC·m-2·a-1.The increase rate can be ranked as:4.5148 gC·m-2·a-1 in the karst area＞3.5596 gC·m-2·a-1 in the study area＞2.7219 gC·m-2·a-1 in the non-karst area.(2)The areas with high NPP values(all greater than 1,200 gC·m-2·a-1)were situated around Fangchenggang City;the areas with low values were scattered along the hydrological line.(3)The trend of Sen showed that the area with an increase of vegetation NPP(77.98％)was significantly larger than the area with a decrease of NPP(22.02％)during 22 years in the study area.Hurst index showed that the regional vegetation NPP values ranged from 0 to 1,averaging 0.65,with a negative skew distribution.(4)The quantitative attribution results of geodetector showed that land use/cover,vegetation coverage and elevation factors were the significant control factors of NPP in the study area,followed by slope and soil type.