榆林地区景观格局分析及其破碎化评价

Landscape Patterns and Fragmentation in Yulin Prefecture

基于1998年榆林地区1∶50万土地利用图,在地理信息系统软件(ArcWiewGIS)和景观格局分析软件Fragstats(栅格版)支持下,从景观总体特征、斑块面积、斑块数、斑块周长、分形维数和结合度指数的角度进行了格局分析和破碎化评价。结果表明,该区草地面积最大,保持的最为完整,以草地、林地和耕地类型为主,三者占全区面积的93 83%。其他类型分布极不均衡,且多呈小面积零散分布。果园、居民地斑块密度较大,说明果园、居民地高度破碎化。同时旱地有最多的斑块数,其斑块密度大于草地和林地,说明它比草地和林地有更高的破碎化。各景观类型的平均斑块面积和周长遵从分形规律,分形维数1 6001,景观整体的斑块边界的褶皱程度不高。草地景观有最高的结合度指数,说明草地的结合度最好,保持的最为完整。上述结果均显示,该区居民地和园地景观破碎化程度较高,旱地比草地和林地有更高的破碎化。

Based on land-use map of Yulin prefecture in 1998(scale 1∶(500 000)), and using the geographic information system program ArcWiew, Arc/Info and landscape analysis program Fragstats3.3, the spatial pattern of Yulin prefecture was analyzed and the degree of fragmentation was evaluated primarily using the overall landscape properties, the area properties, the perimeter properties, the numbers of patches of landscape elements, the double-logged fractal dimension and Patch Cohesion Index (COHESION) for Yulin prefecture. The conclusions are drawn as follows: 1) Grassland is the most important landscape type with the largest area in this region, followed by woodland and farmland. Grassland, woodland and farmland control the overall landscape. The area of grassland, woodland and farmland accounts for 93.83 percent in this region. The other landscape types distribution is very small; 2)The mean patch perimeters of settlement, orchard and water are small, showing a higher degree of fragmentation and little influence on landscape. Grassland has the most heterogeneity in the region, followed by woodland and farmland. Grassland ingredient has the highest border density, showing a strong influence on the overall landscape; 3)The patch density of orchard and settlement is higher than the other landscape types, indicating a higher degree of fragmentation of orchard and settlement. At the same time, dry land has the highest patch numbers, and its patch density is higher than grassland and woodland, indicating a higher degree of fragmentation; 4) Fractal dimension is 1.600 1, showing a low degree of perimeter complexity in the landscape. The grassland has a highest cohesion index, indicating its integrity and least fragmentation; 5) The COHESION index of grassland is the highest ((99.756 3),)and that of the orchard smallest((87.291 2).) All of the results show that the orchard and settlement is highly fragmentized, and grassland has the highest integrity.