Spatiotemporal Variations of Vegetation and its Response to Climate Change and Human Activities in Loess Hilly Area of Western Henan Province, China

Zhijia Gu^1*Keke Ji¹Zixin Li²Ao Li³Yi Shen¹Chong Yao¹Boxiang Yang⁴

• ¹School of Geographic Sciences, Xinyang Normal University, Xinyang, China
• ²School of Geographical Sciences, Fujian Normal University, Fuzhou, Fujian Province, China
• ³Faculty of Geographical Science, Beijing Normal University, Beijing, China
• ⁴School of International Education, Xinyang Normal University, Xinyang, China

Understanding spatiotemporal variations in vegetation and their climatic and anthropogenic factors can provide a crucial theoretical basis for environmental conservation and ecological restoration in the loess hilly area of western Henan Province. However, the spatiotemporal variation and driving forces of vegetation cover in this area under climate change and human activities are still unclear. Therefore, based on the MOD13Q1 NDVI (Normalized Difference Vegetation Index) data from 2000 to 2022, combined with climatic, topographic and human activities data, trend analysis, residual analysis, partial correlation coefficient, and geographical detector techniques were applied to detect the dynamic trends of vegetation changes and their intrinsic relationships with influencing factors. The findings revealed the following: (1) From 2000 to 2022, a comprehensive analysis of satellite-derived vegetation indices revealed substantial enhancements in vegetation cover across 77.5% of the study region, with pronounced improvements documented in five key administrative units: Lushi County, Lingbao City, Luoning County, Mianchi County, and Xinan City. In contrast, due to the rapid expansion of urbanization and the implementation of production and construction projects, the vegetation has been greatly disturbed. Severe vegetation degradation has been noted in Luoyang City, Mengjin County, Gongyi City, northern Lingbao City, Shangjie District of Rongyang City, and Yiyang County, covering 4.4% of the total area. (2) The seasonal difference of loess hilly area in western Henan is significant. The observed vegetation improvement between 2000 and 2022 can be primarily attributed to enhanced spring vegetation growth. (3) Partial correlation analysis indicated that the precipitation had more significant effect on NDVI than temperature. The area of pixels with positive NDVI residual trends accounted for 86.96% of the total area. (4) The observed increase in vegetation NDVI was predominantly attributable to the synergistic effects of climate change and human activities. Land use, elevation, and temperature exhibited consistently high average explanatory contributions, with each factor independently accounting for over 40%. The explanatory contributions of interaction effects was further enhanced compared to that of individual factors, with the interaction between land use and elevation reaching as high as 70.9%. The explanatory contributions of various interacting factors on NDVI showed a gradual increase trend.