Land use/cover change in the Three Gorges Reservoir area, China: Reconciling the land use conflicts between development and protection

Development and protection are both vital human demands in ecologically vulnerable areas. An estimation of the land use/cover changes and their ecological responses could help to understand the regional ecosystem dynamics under various human demands and provide the scientific basis for managing and regulating ecosystems. In this paper, we analysed the spatial-temporal variations in land use/cover types and systematically quantified the relationships between these changes and environmental variables in the Three Gorges Reservoir area. Our results revealed that forestland coverage increased linearly to 53.48%, and that of construction land increased exponentially from 0.25% to 2.75% during 1990-2015. The land use/cover changes exhibited two distinct transformation phases: before and after impoundment. The mutual transformations among vegetation types were significant before 2000, while the forest, water and construction land coverages increased continuously by occupying cropland after 2000. The land use/cover changes were significantly correlated with environmental variables and were sensitive to three topographic variables namely, elevation, surface-height fluctuation and slope. The vegetation dynamics were easily affected by the complex and rugged topography. Moreover, the responses of land use/cover changes varied among topographic variables. The two parameters estimated in the multiple linear regression, elevation and slope, were - 0.164 and - 0.268 for forestland change, -0.391 and 0.378 for water area change, and -0.068 and -0.061 for construction land change. Forest cover was so larger in the regions of higher elevation and steeper slope that afforestation occurred in the regions of moderate elevation and slope. Urbanization and impoundment mainly occurred in the regions of lower elevation, and the regions of steeper slope were more easily submerged, while urbanization mainly occurred in the regions of gentler slope. Therefore, the land use/cover changes due to ecological protection and economic development responded to the interactions among environmental variables and was targeted to different regions to reconcile the land use conflicts, providing a reference for ecosystem management in ecologically vulnerable areas.