三峡库区生境质量的地形梯度效应及对土地利用变化的响应

三峡工程的建设给区域土地利用及生态环境带来巨大变化。在此背景下研究其土地利用和生境质量的时空变化规律,对推进库区国土空间开发保护与高质量发展转型具有重要意义。该研究以三峡库区湖北段为研究对象,根据三峡工程建设时间节点,选取多期土地利用数据,用InVEST模型评估生境质量的时空分异特征,采用分布指数、地形位指数、地理加权回归模型研究其地形梯度效应及对土地利用变化的响应。研究结果表明:1)三峡库区湖北段土地利用的变化特征主要为建设用地和水域大幅扩张,耕地面积小幅增加,林草地面积小幅减少;2)三峡工程一期移民结束后,部分地区生境质量有所提高;一期移民后至三峡工程全面竣工阶段,库区部分城镇周边和三峡大坝附近生境质量退化较明显;三峡工程全面运营后,库区生境质量基本保持稳定;3)从空间分布上来看,位于低地形位的连片城镇化地区与工程建设区生境质量退化程度较大;中地形位零星分布的耕地开垦区域生境质量略有退化;林草覆盖度高的高地形位地区生境质量较为稳定;4)地理加权回归模型显示,生境质量变化对不同地类变化的响应在空间上存在差异。在兴山县南部、夷陵区北部、秭归县南部与巴东县交界处,生境质量对林地变化响应较为显著;在巴东县南部的野三关镇等乡镇生境质量对耕地的变化响应较为显著;在兴山县北部、巴东县城周边、三峡大坝附近生境质量对建设用地和耕地的变化响应较为显著。研究结果有助于揭示三峡库区湖北段生境质量的时空变化过程,为该地区可持续发展及土地利用保护提供决策参考。

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.