Topographic gradient effects of habitat quality and its response to land use change in Hubei Section of the Three Gorges Reservoir

The Three Gorges Project has brought great changes to the regional land use and ecological environment in China in recent years. The temporal and spatial changes in land use and habitat quality are essential to promote the development and protection of territorial space, as well as the transformation of high-quality development in the reservoir area. In this study, land-use data were used from several phases in Hubei section of the Three Gorges Reservoir Area, according to the construction time node. An InVEST model was used to evaluate the spatial and temporal differentiation characteristics of habitat quality. The distribution index, topographic potential index, and geographically weighted regression model were finally utilized to investigate the topographic gradient effect of habitat quality and the response to land-use change. The results showed that: 1) The characteristics of land-use changes in the study area were mainly the large expansion of construction land and water areas, and a small increase in the area of cultivated land, while a small decrease in the area of forest and grassland. 2) The quality of habitats improved in some areas after the first-phase resettlement of the Three Gorges Project. The habitat quality significantly degraded around some cities and towns in the reservoir area and the Three Gorges Dam after the first-phase resettlement to the full completion of the Three Gorges Project. The quality of habitats in the reservoir area remained stable after the full operation. 3) The habitat quality of contiguous urbanization and engineering construction areas located in low topography was degraded to a greater extent, while the habitat quality of cultivated land reclamation areas scattered in the middle topography was slightly degraded, and the habitat quality of high topography areas with high forest and grass coverage was basically stable, from the perspective of spatial distribution. 4) Geographically weighted regression models showed that there were spatial differences in the response of habitat quality to the change of different land types. The habitat quality responded significantly to changes in forestland in southern Xingshan County, northern Yiling District, and the junction of southern Zigui and Badong County. The habitat quality in the villages and towns responded significantly to the changes of cultivated land in the south of Badong County, such as Yesanguan Town. Furthermore, the habitat quality responded significantly to changes in the construction and cultivated land distributed in the northern part of Xingshan County, around Badong County, and near the Three Gorges Dam. The findings can be expected to reveal the temporal and spatial change of habitat quality, particularly providing decision-making references for the sustainable development of land use and protection in the Hubei section of the Three Gorges Reservoir areas.