Abstract: The source region of the Yellow River is one of the ecologically fragile regions in China. In recent years, its ecological environment problems have attracted much attention. Based on the Google Earth Engine (GEE) platform and combined with the remote sensing images of Landsat in the source region from 1990 to 2021, we synthesized six indicators (heat, dryness, air quality, greenness, humidity, and leaf area index) to construct a remote sensing ecological index, which were used to evaluate the dynamics of ecological environment quality in this region. The heat, dryness, and air quality had a negative feedback effect on the ecological environment quality in the source region, while greenness, humidity, and leaf area index had a positive effect, of which greenness was the most critical influencing factor. The area with ecological environment quality improvement accounted for 74.51% of total area of the source region, with an overall spatial pattern of “southern superiority and northern inferiority”. The overall quality of the ecological environment improved during 1990-2021. Over the past 30 years, the ecological environment quality of 89.75% of total area of the source region experienced relatively small changes and maintained good stability. Hurst index analysis showed that the ecological environment quality of 66.36% of total area of the source region had medium and strong sustainability, and that the ecological environment quality in the source region will be better in the future.

Key words: remote sensing ecological index, Google Earth Engine, the source area of the Yellow River, spatiotemporal variation, medium to strong sustainability