Spatial pattern changes of eco-environmental quality in Hami Oasis

Based on the Landsat data of 2000, 2008, and 2018, the remote sensing ecological index (RSEI) was used to determine the ecological environment quality level of Hami Oasis, the 3D trend surface was used to explore the spatial change law of each level of ecological environment quality, and the moving window method was used to analyze the spatial heterogeneity of the ecological environment quality of the oasis and the change of the ecological quality pattern. The results show that: 1) From 2000 to 2018, the average RSEI of Hami Oasis increased from 0.223 to 0.396 and the overall ecological environment quality improved; however, the level was low. 2) In 2000, the regions with medium, good, and excellent ecological environment quality were more concentrated, all on the southeast-northwest axis. In 2008, the areas with extremely poor and poor grades of ecological environment were significantly reduced, and the areas with medium grade, good grade, and excellent grade increased greatly, indicating that the Hami Oasis as a whole expanded rapidly. In 2018, the areas with medium, good, and excellent ecological environment quality were intertwined with each other, mixed, and distributed in a large range, indicating that the ecological quality was not stable enough. 3) The areas where the quality of the ecological environment had improved were concentrated in the interior of the oasis and distributed in a ring-like nest from the inside to the outside. In 2008 and 2018, the ecological index performance from internal to external was determined to be low value area-high value area-low value area-high value area, which was just the opposite of that observed in 2000.