GIMMS NDVI3g+ (1982–2015) response to climate change and engineering activities along the Qinghai–Tibet Railway

Restricted by cold, drought and high altitude natural environments, vegetation ecological environment of the Qinghai–Tibet Plateau is fragile and difficult to repair when damaged. The purpose of this research is to reveal the characteristic of Normalized Difference Vegetation Index (NDVI) in direct impact area and ecological background area response to the engineering activities and global climate changes along Qinghai–Tibet railway. A framework was constructed by integrating a Gaussian fitting model, a buffer analysis, a trend analysis, a correlation analysis and a regression analysis method. The advantages of this framework are (1) Exploration of the impact of human and natural factors on the local vegetation ecological environment in pre-, co-, and post-construction of the railway; (2) Investigation of the time and extent of the impact of engineering activities on the plateau ecological environment; (3) Identify the contribution of climate change and engineering activities to changes of vegetation index. The framework was evaluated with GIMMS (Global Inventory Modeling and Mapping Studies) and MODIS (Moderate Resolution Imaging Spectroradiometer) NDVI from 1982 to 2001–2018. Results demonstrated that (1) Annual NDVI of the Qinghai–Tibet Railway was highly responsive to climate change and engineering activities, and shown a downward trend, upward trend for under construction and in operation period respectively. (2) Engineering activities of the Qinghai–Tibet Railway had a significant impact on vegetation along the route. Annual NDVI growth rate of ‘core area’ and ‘background buffer’ are quite different in pre-construction, under construction and in operation time. (3) Climate change along the Qinghai–Tibet Railway was significantly be responded to global changes during the 34 years. The air temperature and precipitation growth rate of the Golmud South–mountain Pass to Lhasa (GSPL) route is substantial lower than that of the Xining to Golmud South–mountain Pass (XGSP) route. Research results recommend that information on vegetation ecological environment is exploited by government agencies to ensure responsible ecological safety, traffic safety and sustainable development along the Qinghai–Tibet railway.