Spatial and temporal variation of NDVI and its driving factors based on geographical detector: A case study of Guanzhong plain urban agglomeration

Vegetation is an important component of the ecosystem cycle, which is influenced by a combination of natural and human factors, making it challenging to identify the extent of the contribution of its drivers. As one of the nine largest urban agglomerations in China, the Guanzhong Plain urban agglomeration (GPUA) has a fragile ecosystem and severe human disturbance. We concentrated on GPUA as the research object, which used a Geographical Detector to quantify the degree influence of natural and anthropogenic factors on Normalized Difference Vegetation Index (NDVI). The results are as follow, The NDVI showed an increasing trend with an annual growth rate of 0.0088/year. The variation of NDVI showed an obvious spatial pattern. The area of NDVI increased significantly in the southern region, while the significant degradation area was distributed in the northern and central parts. Natural factors contribute more to NDVI change than anthropogenic factors, with precipitation (19.5%), soil type (17.2%) and landform type (16.1%) making the greatest contributions. It was found that the effect of the two-two factor interaction on NDVI was higher than the single factor effect. The research results can effectively identify the variation characteristics of NDVI in ecologically fragile areas under the complex driving mechanism.