汉江生态经济带土地利用格局的地形梯度效应特征

Topographic Gradient Effect of Land Use Pattern in Hanjiang River Ecological Economic Belt

[目的]探究汉江生态经济带土地利用的地形梯度效应,为区域土地利用格局的调整和优化提供科学借鉴。[方法]基于1990—2022年土地利用和DEM数据,选取高程、坡度、地形起伏度和地形位4个地形指标,借助分布指数、信息图谱等分析方法,探讨了汉江生态经济带土地利用格局的地形梯度效应。[结果](1)汉江生态经济带土地利用结构以林地(面积占比在54.59%以上)和耕地(35.20%以上)为主,呈现“东耕西林”空间格局。1990—2022年林地、建设用地和水域面积有所增加,耕地和草地面积减少明显。(2)随各地形梯度等级增加,耕地、水域和建设用地的面积和分布指数逐渐减少,草地均呈先增后减趋势,林地分别呈先增后减、持续增加态势。(3)研究时期内,耕地、林地的分布优势分别在各地形因子的中低(Ⅰ—Ⅲ)和中高(Ⅲ—Ⅴ)等级上有所扩大,其分布指数增幅介于0.041~0.117,0.005~0.076;除Ⅰ级梯度上的分布指数一致呈减少外,其他梯度上草地和水域的分布优势以扩大为主,其指数增加最明显的分别为地形起伏度Ⅲ级(0.317)、地形位Ⅲ级(0.299);建设用地分布优势在Ⅰ级梯度上皆呈扩大态势,其指数增加了0.056~0.689。(4)研究区土地利用信息图谱以稳定型(81.39%)为主,其他图谱类型受地形梯度影响存在显著差异。[结论]受自然、政策等因素的共同影响,汉江生态经济带土地利用格局具有显著的地形梯度效应,分布优势在地形梯度上的变化相对复杂。因此,未来国土空间开发需秉承因地制宜原则,促进土地资源的可持续发展。

[Objective]The aims of this study are to explore the topographic gradient effect of land use in the Hanjiang Ecological Economic Belt(HJEEB),and to provide scientific reference for the adjustment and optimization of regional land use patterns.[Methods]Based on land use and DEM data from 1990 to 2022,four terrain features,namely elevation,slope,relief amplitude and topographic index,were selected to analyze the terrain gradient effect of land use change in HJEEB by used methods such as land use distribution index(DI),information graph.[Results]The land use structure of the HJEEB was mainly composed of forestland and farmland,with an area proportion of over 54.59%and over 35.20%,respectively.In terms of space,there was a pattern of farmland dominated in the east and forest land in the west.From 1990 to 2022,the areas of forestland,construction land,and water areas increased,while the areas of farmland and grassland decreased significantly.As the gradient level of each terrain increased,the distribution area and index of farmland,water area,and construction land gradually decreased.The area of forestland showed a trend of first increasing and then decreasing,while the DI continued to increase.The area and DI of grassland showed a trend of first increasing and then decreasing.The distribution advantages of farmland and forestland during the research period had expanded in the low to medium(Ⅰ—Ⅲ)and high to medium(Ⅲ—Ⅴ)levels of various terrain factors,respectively,with an increase in their DI ranging from 0.041 to 0.117 and 0.005 to 0.076.Except for a consistent decrease in the DI on theⅠ-level gradient,the distribution advantages of grassland and water area on other gradients mainly expanded,with the most significant increase in the DI being relief amplitude levelⅢ(0.317)and topographic index levelⅢ(0.299),respectively.The distribution advantage of construction land showed an expanding trend on theⅠ-level gradient,with DI increase of 0.056~0.689.During the research period,the land use information graph of the HJEEB was mainly stable,accounting for 81.39%of the study area.In addition,there were significant differences in the degree to which various types of land use information graphs were affected by terrain gradients.[Conclusion]Affected by factors such as watershed terrain structure and land use policies(returning farmland to forests,etc.),the land use pattern has a significant topographic gradient effect in HJEEB,and the change of distribution advantage is relatively complex in the topographic gradient.Therefore,the territorial space development needs to adhere to the principle of adapting to local conditions in future in order to promote the sustainable development of land resources.