基于多源数据的三峡库区乐天溪流域林地植被覆盖动态监测

应用多时相、多来源遥感数据,采用图像融合和图像标准化等综合手段,分析了三峡库区乐天溪流域1978—2005年林地植被覆盖度的变化趋势.结果表明:27年来,该区域林地总面积从265.82km2增至346.45km2,植被覆盖度整体上也呈增加趋势,但增加率显现区域不均衡性,植被变化呈现轻度破坏、初步恢复和全面恢复3个发展阶段.林地重心发生了较大的改变.1987年以前,覆盖度<45%的林地重心向北迁移,1987年以后,其重心向南逐渐回归.覆盖度>45%的林地重心则持续从西北向东南逐渐移动.研究区植被覆盖度变化受人类活动干扰、区域经济发展和国家综合治理的影响明显.流域经过10余年的治理,林地植被受人类干扰逐渐减少,覆盖度>60%的林地面积达到217.88km2,占流域林地总面积的62.9%,生态环境逐步得到改善.

Dynamic changes of forest vegetation coverage in Letianxi basin of Three Gorges Reservoir Area: A study based on multi-source data

Based on the multi-temporal and multi-source sensor images of 1987-2005,the dynamic changes of forest vegetation coverage in Letianxi basin of Three Gorges Reservoir Area were investigated by the methods of color balancing,image fusion,and radiometric normalization.The results showed that in 1987-2005,the forest area in the basin increased from 265.82 km2 to 346.45 km2.Vegetation coverage also had an increasing trend,but the increment was not uniform in the whole basin.The change process of the forest vegetation could be divided into three stages,i.e.,slight destroying,starting restoration,and complete restoration.The gravity center of the forests in different coverage classes changed significantly,e.g.,the gravity center of the forests with vegetation coverage less than 45% transferred to the north before 1987,but moved back to the south thereafter,while that of the forests with vegetation coverage greater than 45% moved constantly from northwest to southeast.The changes of forest vegetation coverage in the study area were deeply affected by the human disturbance,regional economic development,and national comprehensive management measures.Through 10 years ecological restoration,human disturbance was decreasing,and the forest area with vegetation coverage above 60% reached 217.88 km2,occupying about 62.9% of the total forest area,which implied that the ecological environment was improved gradually.