山区县域土地利用格局变化及其地形梯度效应——以井冈山市为例

地形是影响土地利用的重要地理因素,山区土地资源禀赋及其开发利用方式深受地形条件限制。以井冈山市为例,采用1995-2015年多期遥感数据,选取坡度、高程、地形位指数等多项因子,通过定性分析与定量评价相结合的方法,深入探讨地形对土地利用类型分布、土地利用动态变化,以及土地利用景观格局的作用机制。研究表明：井冈山市土地利用空间分布具有明显的地形梯度效应,林地、草地多分布在海拔>400 m、坡度>15°的山地和高丘陵区,耕地、水域、建设用地多分布在海拔<400 m、坡度<15°的平原和低丘陵区。研究期内,井冈山市土地利用动态变化主要表现为林地减少和建设用地增加,其中林地净减少992 km²,建设用地净增加352 km²,土地利用方式的改变主要发生在海拔<800 m、坡度<15°、人类活动密集的平原和低缓丘陵地区。土地利用景观格局亦受地形因素影响,在平原和低缓丘陵区,斑块密集分布,景观多样性指数、散布与并列指数、斑块密度及土地利用结构信息熵呈高值分布;而在高海拔、坡度大的山地丘陵区,优势斑块明显,最大斑块所占景观面积的比例以及蔓延度指数呈高值分布。优化山区土地资源配置,促进贫困山区减贫发展,应充分考虑地形因素的影响作用,遵循因地制宜、因势利导和优势开发原则,重视优化土地利用结构与布局,加快推进山区精准脱贫、绿色发展和乡村振兴。

Land use pattern change and its topographic gradient effect in the mountainous areas: A case study of Jinggangshan city

Topography is one of the most important natural environment factors that determines land use pattern, especially in the mountainous areas. Jinggangshan city is located in the Luoxiao Mountains, where the land use activity is extremely limited by terrain conditions. Taking Jinggangshan city as a case study, we selected DEM data and remote sensing data during 1995-2015 to explore the relations between topographical factors and land use pattern. Altitude, slope and terrain niche were chosen as indicators to explain how topographical conditions influence land use spatial pattern, land use change and landscape pattern. Results indicated that land use spatial pattern was affected by the topographical factors. Cultivated land, construction land and water areas were concentrated in plains and gentle rolling hills with altitude <400 m and slope <15°, while forest and meadow were mainly distributed in mountains with altitude >400 m and slope >15°. Moreover, land use transitions had close relations with terrain factors, which mainly occurred in plains and gentle rolling hills with altitude <800 m and slope <15°. The major land use changes during 1995-2015 were featured with 992 km² decrease of forest land and 352 km² increase of construction land. In addition, topographical conditions contributed to the variation of landscape pattern. Patches distributed multitudinously and intensively in plain and gentle rolling hills, which resulted in higher values of landscape diversity index, interspersion juxtaposition index, patch density and land use structure entropy. However, there were scattered and single patches in mountainous areas, so the largest patch index and contagion index were usually high. The terrain difference was an important factor influencing land use structure, land use transition and landscape pattern. It should be taken into full consideration when people determine to change the land use types, especially in the mountainous areas. The reallocation of land resources plays an important role in promoting poverty alleviation and rural development, but it may also jeopardize the natural environment and ecological system. It must be emphasized that people should take appropriate measures to optimize land use types according to local natural conditions. Only in this way can we realize sustainable development.