为探究甘肃农牧交错带植被覆盖度2000—2024年的时空变化趋势,揭示自然和人文因素对其变化的影响程度,基于逐月归一化植被指数(NDVI)遥感数据,使用最大合成法得到逐年NDVI值,通过像元二分法模型反演植被覆盖度,利用空间自相关分析研究甘肃农牧交错带植被覆盖度时空变化特征和空间集聚效应,并借助地理探测器模型分析植被覆盖度变化对自然和人文因素的响应程度。结果表明:1)2000—2024年,甘肃农牧交错带植被覆盖度呈“缓增—骤降”的时序演变特征且区域间存在显著性差异,低、较低植被覆盖类占比超过50%,生态恶化明显。2)植被覆盖度呈现显著的空间分异与聚集特征,空间布局遵循“南高北低、边缘高内部低”规律,南部区域退化程度大于北部,高值集中分布在南部生态屏障区,低值则集中分布在北部过渡区。3)地理探测器结果显示各因素对植被覆盖度变化的影响均显著(P<0.05),其中降水、气温和海拔是核心驱动因子,且因子共同作用的解释力均大于单独作用的解释力,其中降水与各因素交互作用的解释力最大,但人文因子的解释力的持续上升表明人地系统的耦合加深,揭示了研究区植被覆盖度变化是自然与人文因素综合作用的结果。面对全球气候变化和人类活动的双重压力,亟需关注生态脆弱区自然与社会的协同发展并积极探究人地耦合路径,实现区域可持续发展。

To investigate the spatiotemporal variation trend of fractional vegetation cover(FVC)in the agro-pastoral ecotone of Gansu Province from 2000 to 2024 and to elucidate the influence of natural and human factors on its change. This study utilized the monthly Normalized Difference Vegetation Index (NDVI) data,which were obtained by the maximum synthesis method,and FVC was subsequently inverted using the Pixel Dichotomy Model.Spatial auto-correlation analysis and GeoDetector model were employed to examine the spatiotemporal characteristics and spatial agglomeration effect of FVC,as well as to quantify its response to natural and human factors. This study indicated:1)From 2000 to 2024,the fractional vegetation cover in the agro-pastoral ecotone of Gansu Province exhibited a temporal trend of "gradual increase followed by a sharp decline" with significant differences between regional variation,and the proportion of areas with low and lower medium vegetation coverage exceed 50%,indicating significant ecological degradation.2)FVC showed significant spatial heterogeneity and clustering.Its spatial distribution followed the a pattern of "higher in the south and lower in the north,higher at the periphery and lower in the interior". The degradation degree of the southern region was worsethan that of the northern.High FVC value was concentrated in the southern ecological barrier region,where as the low values were clustered in the northern transition zone. 3)The Geo Detector results showed that all factors had significant effects on FVC change (P<0.05),with precipitation,temperature and elevation being the core driving factors. The explanatory power of the factors interactions was consistentlygreater than that of any single factor,with the interaction between precipitation and other factor sbeing the most powerful. However,the increasing explanatory power of human factors suggests the deepening coupling of human-environment system. In the face of the dual pressure of global climate change and human activities,it is urgent to pay attention to the coordinated development of nature and society in ecologically fragile areas and actively explore the human-environmentcoupling pathway to achieve regional sustainable development.