吉林省西部草地景观空间格局动态变化研究

利用1980，1995，2000年3期遥感影像，在RS与GIS技术支持下，解译提取吉林省西部20年草地景观类型空间信息，选取景观优势度、破碎度、分维数、分离度和平均斑块伸长指数，对吉林省景观空间格局的时空动态演变进行分析．结果表明：研究区草地景观面积、斑块数减少，草地退化严重；草地景观分布动态变化趋于均匀，优势景观类型优势度降低，斑块空间形状简单，高、中覆盖度草地斑块形状多狭长，呈带状；1980～1995年各种类型草地景观破碎化程度降低，1995～2000年破碎化程度加强，总体动态变化呈现出增强趋势；20年来各种类型草地的质心整体向东北方向偏移，不同阶段各种草地景观质心偏移表现出无规律性、多向性，1980～1995年高、中、低覆盖度草地质心分别向东北、西南、西北方向偏移，而1995～2000年高、中、低覆盖度草地质心则分别向西北、东北、东南方向偏移．自然因素对研究区草地景观动态变化起到一定的驱动作用，人类活动干扰则是主要驱动力。

Dynamic changes in grassland landscape pattern in Western Jilin Province

Based on RS images from three periods(1980, 1995, 2000) and with the support of RS and GIS, spatial information of grassland landscape in Western Jilin Province during 1980~2000 is extracted and, by using the models of landscape dominance, fragmentation, mean patch fractal dimension, isolation and mean patch elongation index, dynamic spatio-temporal changes in grassland landscape patterns of Jilin Province is analyzed. The results indicate that, in the study region, both the area and the number of grassland landscape decreased and grasslands degraded severely; Dynamic change of grassland landscape distribution has a tendency of being even and the dominant landscape becomes more and more indistinct, spatial shapes of patches are simple, patch shapes of high and moderate coverage grassland are getting long and narrow, and becomes strap-shaped. From 1980 to 1995, the fragmentation degree of various grassland landscapes declined but the degree increased during 1995~2000, and the total dynamic change shows a tendency of increasing; During 1980~2000, the centroids of various grasslands moved towards the northeast direction and centroid change of each type of grassland landscape were irregular and multi-directional in different stages. From 1980 to 1995, the centroids of high, moderate and low coverage grassland moved towards northeast, southwest and northwest respectively, but during 1995-2000, the centroids of high, moderate and low coverage grassland moved towards northwest, northeast and southeast respectively. As far as the dynamic change of grassland landscape in the study area is concerned, natural factor takes certain driving action but human activities are the main driving force.