渭北旱塬县域土地利用时空演变规律研究——以合阳县为例

Land use dynamics in Weibei upland in China— A case study of Heyang County

为探讨渭北旱塬区土地利用时空变化规律,本研究以陕西渭北合阳县为研究区,在GIS与RS等技术支持下,以1990年、2000年Landsat TM影像以及2010年SPOT影像为数据源,运用地学信息图谱及土地利用转移矩阵的方法,对1990—2000年、2000—2010年2个不同时段土地利用数量变化及类型的空间转换特征进行了分析。结果表明:(1)20 a间合阳县耕地面积减少了31.25 km2,耕地主要转化为草地、林地、建设用地、水域。园地面积增加了21.26 km2,增幅达146.6%,主要由耕地、草地及林地转化而来。(2)研究区土地利用变化图谱以稳定型图谱和后变型图谱为主。稳定型图谱占全区总面积的86.66%,后变型图谱占全区总面积的7.32%。说明研究区土地利用类型图谱变化总体比较平稳,部分变化也主要发生在2000—2010年间。(3)研究区20 a间土地利用格局呈现一定的层次性。耕地、建设用地和水域主要分布在地形变化不大或地势较低的区域;草地及林地主要集中分布于中高地形梯度内;林地和未利用地在高地形梯度内呈现优势分布。地形与人类活动是该区土地利用/覆盖变化(LUCC)的主要因素,政策导向与市场经济需求对LUCC也有较大的影响。该研究结果为区域土地利用空间格局的优化配置提供科学依据,为生态建设规划提供决策支持。

Spatial-temporal evolution of land use and landscape pattern has become a core component of research on land use and cover change. In order to understand the spatial and temporal change characteristics of land use of Weibei upland, Heyang County, we used the geo-informatics TUPU, land use transfer matrix and the Markov model to evaluate quantitative characteristics of changes and spatial transfer of the land use types in this area based on interpretation data form TM image in 1990 and 2000 and SPOT image in 2010. The driving forces of land use change were also analyzed in this research. The results showed obviously hierarchical distribution of land use types. Crop land, mining and construction land and water body were distributed in area of terrain relief under 25 m as well as slope of slope（SOS） less than 3°. During the past 20 years, crop land was the dominant land use type. Grass land and forestry land mainly distributed on middle or high terrain gradient. Forest land and unused land were the dominant land use types on the area of high terrain gradient. From 1990 to 2010, the area of arable land decreased continuously, from 893.13 km2 in 1990 to 861.88 km2 in 2010, and arable land mainly transformed into grass land, forest land, mining and construction land and water body. Area of orchard increased obviously, from 14.54 km2 in 1990 to 35.76 km2 in 2010, mainly transformed from arable land, grass land and forest land. There had 5 land use change TUPU types： the stable type, anaphase type, prophase type, transform type and constant type. Stable type and anaphase type were the dominant types in the study area from 1990 to 2010. The areas of stable type and anaphase type accounted for more than 86% and 7% of total area, respectively. The other land use change TUPUs occupied low proportions of total area. This indicated that land use changes were gently in this area, land use changes mainly occurred during 2000 to 2010. Landform and anthropogenic activities was the main factors driving land use cover change（LUCC）. Moreover, the policy guidance and market demand for LUCC also had a greater impact on LUCC. The study provided scientific theoretical basis for the dynamic optimal configurations of land use pattern and the decision support of construction of eco-environment of Heyang County.