Abstract: Chengdu-Chongqing economic circle is an important water conservation area and the core area of ecological construction in the upper reaches of the Yangtze River. Comprehensive evaluation of the quality of ecosystems and environment should be aiming to grasp the spatiotemporal responses of habitat quality to urban sprawl, which is of great significance on the construction of ecological security pattern and the maintenance of biodiversity. Based on the land use data of Chengdu-Chongqing area in 2000, 2010 and 2020, the land use degree index, land use dynamic attitude index, InVEST model and bivariate space autocorrelation model have been employed to analyze the spatial-temporal evolution characteristics of habitat quality and the intrinsic connection. The results show that, (1) The main types of land use in Chengdu-Chongqing area are cultivated land and forestland, which account for more than 86% of the study area. Over the 20 years, the cultivated land and grassland declined significantly, while the construction land continued to expand, increasing by 148.88%. In comparison with the period of 2000-2010, the conversion of land use in the period of 2010-2020 was more complex, and the dynamic attitude of comprehensive land use increased by 2 times. (2) The habitat quality of Chengdu-Chongqing area was in the medium level or above. The spatial pattern of habitat quality exhibited a low level in "Chengdu Circle and Chongqing Circle" area, medium level in middle area and a high level in surrounding areas. During the 20 years, the proportions of areas with constant, decreasing and increasing habitat quality in the study area were 72.52%, 22.70%, and 4.78%, respectively. In the area of decreasing habitat quality, more than 20% of high-quality habitats lost their ecological functions. (3) There was a significant negative correlation between land use degree and habitat quality in Chengdu-Chongqing area, and the correlation was increasing, and the spatial aggregation in this area is dominated by high land use degree-low habitat quality and low land use degree-high habitat quality.

Key words: Chengdu-Chongqing area, habitat quality, land use, InVEST model