黄土高原归一化植被指数与自然环境因子的空间关联性——基于地理探测器

植被对改善黄土高原脆弱的生态环境有着关键作用,系统研究黄土高原归一化植被指数(NDVI)空间分布和环境因子的空间关联性,可为新时代黄土高原植被高质量建设提供科学依据。以黄土高原2000-2017年年均植被NDVI为研究对象,选取气候要素、地形因素、土壤类型和植被类型等自然环境因子,运用GIS和地理探测器技术手段,在剔除土地利用类型发生变化栅格的基础上,研究黄土高原年均NDVI与环境因子的空间关联性,结果表明:2000-2017年黄土高原年均NDVI值在0.016-0.72之间,呈地带性分布,由西北部向东南部逐渐升高,大于0.3的区域占50.23%;2000-2017年黄土高原年均植被NDVI分布具有空间异质性,且在不同植被区、地貌区、土壤区和气候区中,NDVI空间分布的主要环境驱动因子具有差异性。年均降雨量对NDVI空间分布具有强解释力,是黄土高原85.20%的区域植被生长的主要制约因子;约12.01%的区域主要受土壤类型影响,为中等解释力,其余区域的植被生长主要受年均气温,日照时数或海拔影响。建议综合考虑不同环境条件下植被NDVI的空间分布与环境影响因子的空间关联性,明确不同区域中植被NDVI的环境制约因子,以制约因子定植,在防止土壤干燥化、贫瘠化的前提下,提高植被覆盖率和生物多样性,以期促进黄土高原植被建设高质量发展。

Spatial correlation analysis between vegetation NDVI and natural environmental factors based on geographical detector on the Loess Plateau

Vegetation plays a key role in improving the fragile ecological environment of the Loess Plateau. The spatial correlation between normalized difference vegetation index (NDVI) spatial distribution and environmental factors can provide a scientific basis for the high-quality construction of vegetation on the Loess Plateau in the new era. In this study, the spatial correlation between natural environmental factors (climate, topography, soil types and vegetation types) and NDVI from 2000 to 2017 on the Loess Plateau was analyzed by GIS and geographical detector on the premise of eliminating the grid with changes in land use types. The results indicated: (1) from 2000 to 2017, the average annual NDVI on the Loess Plateau ranged from 0.016 to 0.72, which showed a gradually increasing zonal distribution from northwest to southeast, with 50.23% of the areas greater than 0.3. (2) The annual average vegetation NDVI distribution showed spatial heterogeneity, and climate factor and vegetation type had strong explanatory power on the spatial distribution of NDVI, followed by soil type, while topographic factor had weak explanation. (3) In the vegetation zones, different soil zones, geomorphic zones and climate zones, the main environmental driving factors of NDVI spatial distribution were different. The average annual rainfall was the main environmental driving factors of NDVI spatial distribution with different explanatory power in aridisols zones, desert soil zones, entisols zones and each geomorphic zones. In the rest of zones, the main environmental driving factors of NDVI spatial distribution were soil type, vegetation type, sunshine duration or relative humidity. (4) The average annual rainfall had a strong explanatory power in the spatial distribution of NDVI and was the main environmental restricted factor for 85.20% of regional vegetation growth on the Loess Plateau, with 12.01% mainly influenced by soil factors, and the rest of region was affected by annual average temperature, sunshine duration or elevation. In conclusion, there was a strong spatial correlation between environmental factors and vegetation NDVI distribution on the Loess Plateau. However, due to the complexity of the geographical process of the Loess Plateau, the spatial correlation between environmental factors and vegetation NDVI had significant differences under different environmental conditions. Therefore, it is necessary to determine plant types in vegetation construction according to the environmental restricted factors of NDVI spatial distribution. It will improve the vegetation coverage and biodiversity on the premise of preventing soil desiccation and impoverishment, and promote the high-quality development of vegetation construction and ecological environmental protection on the Loess Plateau.