Comprehensive evaluation and evolutionary characteristics of eco-environment quality in Qilian Mountain National Park

Qilian Mountain National Park serves as a vital ecological security barrier in Western China, but mining, hydroelectric development, and overgrazing have resulted in serious ecological and environmental damage. Using remote sensing as well as meteorological and socio-economic statistical datasets of 14 counties in Qilian Mountain National Park from 2000 to 2018, this study established an assessment indicator system for eco-environmental quality. We also employed the principal component analysis method to determine the contribution of each indicator, which was then used to develop a new eco-environmental quality index (EQI). The spatiotemporal variations in the EQI and its influencing factors were examined. The results showed that the spatial distribution of mean annual EQI was characterized by low values in the west and high values in the east of Qilian Mountain National Park. The EQI varied significantly for the different counties. During the study period, the EQI of the national park showed a significant increasing trend (P < 0.01). The smaller the average EQI, the slower the rate of increase. Natural factors were the major driving force for the temporal variation of eco-environmental quality, followed by economic and social factors, showing a contribution of 52%, 28%, and 20%, respectively. The mean annual temperature and precipitation, annual average radiation, vegetation coverage, enhanced vegetation index, leaf area index, net primary productivity, gross output value of forestry, amount of livestock raised, grain planting area, value-added index of primary industry, per capita GDP added value index, natural population growth rate, the number of educated people, urban and rural household savings, per capita net income of rural residents, and non-agricultural population played a positive role. Value added index of secondary industry, value-added index of tertiary industry, agricultural population, and other indicators played a negative role. Our findings suggest the need for further implementation of natural forest protection, returning farmland to forest, and forbidden grazing programs in the future. Decision-makers need to improve the ecological compensation mechanism and eco-environment supervision. Strict limits on the intensity of human activities in the central and western parts of the national park should be set to promote the restoration of a fragile ecological environment.