Normalized difference vegetation index (NDVI) is an important indicator reflecting vegetation cover and growth status. It is of significance for regional ecological conservation and natural resource management to investigate its spatial and temporal variation trends and response to ecological factors. We divided Liaoning Province into three ecological geographical regions, including northwest agro-pastoral zone, central agricultural zone, and eastern agroforestry zone. Based on remote sensing, vegetation, climate, topography and human activities, we used trend analysis and geographic probe model to examine the spatial and temporal trends of NDVI in Liaoning Province, and analyzed the intensity and interaction mechanism of each driver on the spatial distribution pattern of NDVI. The results showed that the annual average NDVI in Liaoning Province from 2001 to 2020 was 0-0.92, showing a distribution pattern of high in the east and low in the west, high in the inland and low in the coastal land. The overall trend of vegetation cover was increasing, and the NDVI increasing areas were mainly concentrated in the northwest agro-pastoral zone and the eastern agroforestry zone, the NDVI reduction areas were mainly concentrated at the border between the central agricultural zone and the eastern agroforestry zone, as well as in the coastal area of the eastern agroforestry zone. The annual average NDVI change varied among the three ecological-geographic zones. The NDVI of the northwest agro-pastoral zone from 2001 to 2020 were generally low, but showed a fluctuating trend of slow increase. The NDVI of the eastern agroforestry zone was high overall, and the interannual variation of NDVI was generally stable. The distribution of high and low NDVI in the central agricultural zone was staggered, and the interannual variation of NDVI showed a decreasing trend. Natural factors were the key drivers of NDVI changes in the three ecogeographic zones, with cumulative temperature and precipitation having the greatest influence. The interactions between the factors were all mutually and nonlinearly enhanced.
归一化植被指数(NDVI)是反映植被覆盖及其生长状况的重要指标,探究其时空变化以及对生态因子的响应,对区域生态保护和自然资源管理有重要意义。本研究将辽宁省分为3个生态地理区(西北农牧交错区、中部农业区、东部农林区),基于遥感、植被、气候、地形和人类活动等数据,采用趋势分析法和地理探测器模型,揭示了辽宁省植被NDVI的时空变化趋势,以及各驱动因子对辽宁省植被NDVI分布格局的影响强度和交互作用机制。结果表明: 2001—2020年,辽宁省NDVI年均值在0～0.92,呈现东部高西部低、内陆高沿海低的分布格局。植被覆被整体呈增加趋势,其中,NDVI增加的区域主要集中在西北农牧交错区和东部农林区;NDVI减少的区域主要集中在中部农业区与东部农林地区的交界处,以及东部农林区沿海一带。3个生态地理分区的年均NDVI变化各不相同,其中,西北农牧交错区NDVI整体偏低,但呈缓慢上升的波动趋势;东部农林地区NDVI整体偏高,NDVI年际变化基本稳定;中部农业区的NDVI高值和低值错落分布,NDVI年际变化呈减少趋势。3个生态地理分区中,自然因子是NDVI变化的关键驱动力,其中,积温和降水的影响最大。各因子间的交互作用结果均为相互增强和非线性增强。.
Keywords: Geodetector; Liaoning Province; eco-geographic zoning; normalized difference vegetation index; trend analysis.