Abstract:

As an inland river in the northwest arid zone, the Aksu River Basin hosts a fragile ecological environment. Studying its ecological security pattern is of great strategic significance for optimizing the national territory development and protection pattern, promoting the green transformation of production and lifestyle, and promoting the harmonious coexistence of man and nature. On the basis of the background characteristics of the study area, a spatial principal component analysis was undertaken to evaluate and monitor the temporal and spatial evolution of the ecological carrying capacity of the Aksu River Basin in Xinjiang, China in 1980, 2000, 2006, 2012, and 2018; the minimum cumulative resistance (MCR) mode was used to extract ecological corridors and ecological nodes in order to construct a comprehensive pattern of ecological security. The research results show that (1) the ecological carrying capacity of the river basin has significant spatial variations. The ecological carrying capacity of the Aksu River Basin is, for the most part, classified as being of medium carrying capacity, and the area with the highest ecological carrying capacity shows a trend of shifting from the central and eastern regions toward the west. The areas of strongest carrying capacity are predominantly located in the middle of the river basin and are distributed along the river in a zigzag pattern. The ecological carrying capacity of the upper and lower reaches of the river is relatively weak. The strong load-bearing areas are mainly distributed along the Toshigan River, Kumarak River, and the alluvial plains of the Aksu River; weak load-bearing areas are predominantly distributed on the northwestern edge of the Taklimakan Desert, the Tarim Basin, and the southern part of the Tianshan Mountains. (2) The ecological carrying capacity of the basin has shown an increase over time: In the past 40 years, the overall ecological carrying capacity of the Aksu River Basin has shown an upward trend, the acreage of strong carrying areas has been increasing, and the acreage of weak carrying areas has shown a fluctuating downward trend. These trends indicate that the basin environment has improved. The ecological carrying capacities of Akqi County, Wensu County, Wushi County, and Aksu City have showed an upward trend, whereas that of Alar City has showed a downward trend, and that of Awati County has remained roughly unchanged. (3) The ecological source area occupies a relatively small area, and the distribution is relatively concentrated. Through the assessment of the ecological carrying capacity of the Aksu River Basin, 23465.21 km² of ecological source area was finally extracted, accounting for approximately 35.61% of the study area. The ecological sources are concentrated in the central area of the basin, whereas they are less concentrated in the northern alpine areas, southwestern basins, and desert areas. (4) The ecological corridors are unevenly distributed, and the ecological nodes are relatively fragile. Using the MCR model and remote sensing images, the author divided the Aksu River Basin into 16 ecological security pattern zones, extracted 67 ecological corridors in the basin, and found that the ecological corridors are distributed around the river and predominantly concentrated in the central and eastern regions, with a small number present in the western region. The author also used commercial software to identify 71 ecological nodes, of which 20 are located between ecological sources, 16 are located in river flow areas, and 35 are located in mountain or piedmont areas. This work will make suggestions for optimizing the ecological spatial structure of the basin on the basis of the results of the evaluation of the ecological carrying capacity.

Key words: ecological carrying capacity, spatial and temporal evolution, ecological security pattern, optimization, Aksu River Basin