近25年长江中游地区土地利用时空变化格局与驱动因素

长江中游地区(湖北省、湖南省和江西省)位于长江经济带中心,是我国"中三角城市群"所在地,也是国家"两屏三带"生态安全战略的重点区域,其土地利用变化受地理环境制约和社会经济发展的影响,也与未来区域可持续发展密切相关。根据1990、2000、2010和2015年Landsat TM遥感影像数据,采用景观格局分析、梯度分析及相关性分析方法,揭示近25年土地利用时空变化格局及其与社会经济因素的关系。研究表明:(1)研究区耕地与林地为主体景观,分别占30%、50%,建设用地占比3%,具有重要生态功能的土地利用类型(林地、灌木、水体、草地、果园)占比达67%。(2)沿中心城区-边缘区梯度,各土地利用类型表现出明显的空间特征,建设用地和耕地面积占比显著减小,破碎化程度增加,而林地呈整体化趋势。(3)近25年来,该区耕地、林地分别减少1.06%、0.49%,建设用地增加1.08%,整体景观破碎化程度加重、景观多样性升高;除林地外,其它地类变化均与社会经济因素(人口、农业人口、非农业人口、GDP、人均GDP、城市化水平、三大产业产值)显著相关。这些结果表明,与沿海地区相比,近25年长江中游地区土地利用变化较小,还有着较好的基于提供生态系统服务的土地利用基础;但生态保护任务仍然艰巨,需划定生态保护红线,保护优质耕地,控制城市扩展规模,加强生态廊道、节点的建设,增强区域景观生态功能,以便满足未来长江经济带可持续发展的需要。

Temporal and spatial variations of land use and the driving factors in the middle reaches of the Yangtze River in the past 25 years

The middle reaches of the Yangtze River (including Hubei, Hunan, and Jiangxi Provinces) and the "Central Triangle City Group" are located in the center of the Yangtze River Economic Belt and are one of the key national ecological security areas. The land use pattern of this region is not only affected by the local geographical environment and social and economic development but also will be closely associated with the sustainable development of the future social environment. Based on the Landsat TM remote sensing images of 1990, 2000, 2010, and 2015, this study reveals the temporal and spatial patterns of land use change and their relationships with socio-economic factors in the past 25 years by means of landscape pattern analysis, gradient analysis, and correlation analysis. The results showed (1) the cropland and forest land areas were the dominant land types (30% and 50%, respectively), and the proportion of construction land was < 3%. The land use types (forest land, shrub, water body, grassland, and orchard) with important ecological functions accounted for 67%. (2) Along the central city-edge area gradient, each land use type showed obvious spatial characteristics. In particular, the proportions of construction land and cropland areas significantly decreased, the degree of fragmentation increased, while the forest land tended to be integrated. (3) In the past 25 years, cropland and forest land decreased by 1.06% and 0.49%, respectively, and the construction land increased by 1.08%. The degree of regional landscape fragmentation and the landscape diversity increased. Except for forest land, all land use types were significantly related to socio-economic factors (population, urbanization levels, output values of three industry sectors, etc.). These results suggest that, on the one hand, compared with the coastal city group, land use changes in the middle reaches of the Yangtze River have been relatively small, and there is a good basis of land use types for the provision of ecosystem services. On the other hand, there is a great challenge for ecological protection in this region. The main measures are to delineate the red line of ecological protection, protect high-quality cropland, control the scale of urban expansion, strengthen the construction of ecological corridors and ecological nodes, and enhance the ecological functions of regional landscapes in order to meet the needs of sustainable development of the Yangtze River Economic Belt in the future.