川西丘陵区景观空间格局分析

Analysis of landscape spatial patterns in the hill region in the west of Sichuan Basin

采用分形维数、平均斑块面积、形状指数和伸张度分析了川西不同丘陵地貌区灌溉水田、一般旱地、果园、有林地和农村居民点斑块的空间格局特征 ,并用分形维数、平均斑块面积和 Shannon- Weiner指数 3种方法研究了浅丘、中丘和高丘的综合景观特征。结果表明 ,不同景观斑块在同一丘陵区内的格局特征不同 ,同一景观斑块在 3种丘陵区的格局也有差异。浅丘、中丘和高丘的综合景观格局特点是随着地势起伏的增加、人类活动和土地利用强度的减弱 ,分形维数增加 ,从 1 .1 865到 1 .31 2 3;斑块平均面积则依次变小 ,从 2 .2 2 0 4 hm2 减少到 1 .2 4 0 3hm2 。 3种丘陵区的景观多样性指数分别为 1 .71 99、1 .980 2和 2 .0

The spatial pattern characteristics of irrigation terrace, upland field, orchard, forest and residential were studied with fractal dimensions, mean patch area, shape index and elongation in the different hilly regions in the southwest of Mingshan County, Sichuan Province, China. Among the research approaches, the fractal dimensions were calculated by the perimeter-area based on the logarithm relationship between perimeter and area of a landscape patch. From east to west, the relief of low, middle and high hill appears in the research district. Its total area of the regional area was 853.1hm2, in which those of low, middle and high hill were 250.9 hm2, 310.7 hm2 and 291.5 hm2, respectively. The landscape patch map was obtained from aerial photography by the X-3 parallax map measurer after field investigation. On the map the patch number for each landscape type was determined according to the total patch number of this one in certain hill region. 5~7 patches for irrigation terrace, upland field, orchard, forest and residential according to the number were sampled randomly, respectively. The research results of this paper indicated that the patch pattern of one landscape element among the five types was different from that of other one in the same hilly region, and the spatial pattern of the same type varied in the three hilly regions. In low hill, irrigation terrace is absolutely essential factor in this region. Its patches distribute in the bed and sides of the gulches with fine irrigation condition. The patches of residential are centralized relatively at the foot of the hill with fine traffic. Upland field, orchard and forest scatter the upper part of the hill or the place being irrigated difficultly. The fractal dimensions of irrigation terrace were 1.1024, and the smallest among the five types. Otherwise, the dimensions for residential were the largest among the five types because the patch shapes were more complex than those of the other types. From the patch size, mean patch area of irrigation terrace is 7.2180 in low hill so that the landscape type was regard as the background of this region. The value of shape index for the irrigation terrace was the largest among them but the patch shapes of upland field and orchard were close to circle. The elongation for the residential was the smallest among the landscapes. In middle hill, the distribution of forest and unused land was more than those in low hill and the landscape patches appeared strip. The former distributed in the middle and foot parts of the hill and the later in the upper part of the hill with stripe. The distribution upper boundary of irrigation terrace went down, and centralized on the gulch bed. Its fractal dimensions for the landscape type were from 1.2109 to 1.4072. The patches of Irrigation terrace, upland field and forest were larger than those of the other two types in the region. From the shape index, the shapes for orchard and residential were closer to circle than those of the other three landscapes. The elongations of the landscape patches varied from 0.2208 to 0.5276. In the high hill, the land was developed weakly in the three regions and patterns of the landscapes patches were more complex and diverse. The fractal dimensions of forest patches were the highest among the five landscape elements and those of orchard, residential, and irrigation terrace reduced in order. From the mean patch area, the patch areas of upland field and forest were larger than those of the other three types. The elongation of the five types was obvious but only residential shapes were close to circle. The comprehensive pattern characteristics in the low hill, middle hill and high hill were that the fractal dimensions increased from 1.1865 to 1.3123, and mean patch area became smaller and smaller, from 2.2204hm2 to 1.2403 hm2 with the relief increment, and reduction of human activities and landuse. The diversity indices were 1.7199, 1.9802 and 2.0899 in the three hilly regions, respectively. Therefore, human activities and landuse resulted in decrease of landscape