大兴安岭林区道路网络对景观格局的影响

Impacts of road network on forest landscape pattern in Great Xing'an Mountains of Northeast China

在明确大兴安岭呼中林业局道路网络系统组成特征的基础上,利用主成分分析法,将林业局内17个林场作为分析单元,以该林业局1989年景观为例,对有、无道路情况下的景观格局分别进行定量分析,探讨了道路对森林景观格局的影响.结果表明:呼中林业局内包括运材主、支路在内的常年运材路密度为2.3m.hm-2,在各个林场内分布均匀,基本沿着河流水系深入到各个采伐区.道路的出现使景观水平上的森林格局发生了显著变化:所有林场中,平均斑块面积减少、数量增多、斑块间距离增大,均表现出不同程度的破碎化,但破碎化程度与道路密度之间没有显著的相关性;道路网络对景观破碎程度的影响比对空间聚合程度的影响更强烈.

By characterizing the composition of road network in the Huzhong Forestry Bureau in Great Xing＇an Mountains,Northeast China,we investigated the effects of road networks on landscape pattern by quantifying 1989 landscape pattern for each of the 17 forestry farms on maps with and without roads by principal component analysis（PCA）.The results showed that road networks,including the main and secondary timber-transport roads,were distributed evenly among the observed 17 forestry farms with a density of 2.3 m·hm-2 and spread along the river networks throughout each farm.The emergence of roads significantly altered the landscape pattern at the landscape level in each farm,which was characterized by landscape fragmentation involving a decline in patch area and an increase in patch number and distance among patches.Furthermore,no significant correlation was found between fragmentation and road density.The road network had more impact on fragmentation than on aggregation at the landscape level.