北江干流河岸缓冲带景观格局的梯度效应分析

Gradient effect analysis for landscape pattern of the Beijiang River riparian buffer zone

基于2000、2005和2010年的TM遥感影像,结合GIS和RS技术,采用缓冲区分析方法研究了北江干流10km河岸缓冲带景观格局特征及其水平梯度效应。结果表明,10 a间,林地是景观基质,其次是农田和水体;农田、草地和灌丛呈减少趋势,建设用地和未利用地呈增加趋势,林地和水体先增加后减少。在类型水平上,各景观组分的复杂度呈下降趋势,破碎化呈现先上升后下降状态,而连接度呈现增强的趋势;在景观水平上,最大斑块和凝聚度指数在0~1 km有明显的峰值,形状指数随着缓冲区宽度的增加逐渐上升,而聚集度指数与凝聚度指数呈现相反的趋势。

Based on three sets of TM images（ 2000,2005 and 2010）,GIS and RS techniques,we studied the characteristics of landscape pattern and its gradient effect within 10 km buffer zone along the Beijiang River using the method of buffer analysis. The results showed that in the period of 2000 ~2010,forest land was the landscape matrix of the study area,followed by cultivated land and water area. Cultivated land,grass land and shrub land presented the tendency of decreasing,while the construction land and unused land presented the tendency of creasing; forest land and water area decreased first and then increased. In terms of landscape types,the complexity of different kinds of landscape declined,while connectivity was in adverse. Fragmentation increased first and then decreased.At the landscape scale,values of the largest patch index（ LPI） and COHESION showed distinctive peaks because water area occupied dominant position within 1 km buffer zone and the landscape type was simple. Landscape shape index（ LSI） increased with the increasing width of the buffer zone,while the aggregation index（ AI） presented a completely reverse tendency.