嫩江河岸带景观格局变化对水体恢复的影响

利用景观生态学原理,以1976年的Landsat MSS遥感影像和1989,2000,2005,2008年的Landsat TM/ETM遥感影像为数据源,研究了嫩江干流及其10 km河岸带不同景观类型以及河岸带整体的景观格局变化对嫩江水体及其恢复的影响。结果表明,嫩江经过近30 a余的演变,水体面积增加,景观破碎化程度降低,河道蜿蜒度明显减小从而不利于嫩江生物多样性恢复。河岸带内耕地景观格局的变化可加剧嫩江水质恶化,河岸带整体景观格局的演变也不利于嫩江水体自然恢复。但从2000年起,林地景观格局变化在一定程度上将会有利于嫩江水质和生物多样性恢复,这主要得益于退耕还林还草,植树造林等一系列政策和生态工程的实施。

Influence of Landscape Pattern Changes of Nenjiang River Riparian Zone on Stream Restoration

Taking the buffer zone with the width of 10 km along the main stem of Nenjiang River as astudy area,based on the theories of landscape ecology,the influences on the stream restoration of landscape pattern changes of each individual type and the whole landscape were studied using Landsat images of 1976,1989,2000,2005,and 2008.The results showed that over the past 30 years,area of the water body of Nenjiang River decreased,extent of fragmentation of the landscape decreased,and the degree of meandering of the river decreased,all of which are not in favor of the restoration of biodiversity.The changes in farmland patterns exacerbated the deterioration of the water quality of Nenjiang River,and the changes in the whole landscape configuration did not favor the natural restoration of waters as well.However,since 2000,the changes in the forestland and wetland patterns to some degree favored the biodiversity restoration and water quality improvement of the river,as a result of the implementation of a series of ecological reconstruction policies and projects including returning farmland to forestland and grassland,planting tree and afforestation,protecting wetland.