Abstract: Land use change affects ecosystem structure and function. Evaluating the ecological environment effect of land use change can provide a basis for regional ecological protection. We analyzed the land use change, ecological environmental effects, and influencing factors of Danghe River source region, with Landsat remote sensing images in 1987, 1994, 2000, 2006, 2011 and 2017 as the main data source, using the remote sensing ecological index (RSEI) and plant community survey methods. The results showed that from 1987 to 2017, the areas of natural pasture, marshland, and bare rock gravel land in Danghe River source region showed a decreasing trend, while the areas of marsh grassland, river surface, sandy land, glaciers and permanent snow exhibited an increasing trend. The area with excellent and good ecological grades increased by 14.26%, while the area with poor and inferior ecological grades decreased by 27.9%. The RSEI increased from 0.48 in 1987 to 0.57 in 2017. The 6-year average value of RSEI in natural pasture, marsh grassland, and marsh was higher than that in sandy land and bare rock gravel land. The RSEI value of natural pasture, marsh grassland, and sandy land showed an overall upward trend, while that of marsh showed an overall downward trend, and that of bare rock gravel land had no obvious trend. There was a significant positive correlation between precipitation and the RSEI value of marsh grassland, natural pasture, and marsh land (all P<0.05). There was no significant correlation between RSEI value of sandy land, bare rock gravel land and annual precipitation, mean annual temperature, livestock inventory (P>0.05). The superposition of climate warming, humidification and socio-economic factors promoted the evolution of landscape types and improved the quality of ecological environment in the Danghe River source region.

Key words: land use change, remote sensing based ecological index (RSEI), plant community investigation, Danghe River source region.