大兴安岭林区道路对植物多样性的影响域

Effect zone of forest road on plant species diversity in Great Hing'an Mountians

道路在多种尺度上影响多种景观过程,确定道路对植被的影响距离和估算其影响面积是整合道路影响和生态过程的核心问题.本文在黑龙江省大兴安岭呼中林区选择不同等级道路(呼林主路、运材主线和运材支线)设置10条长50m垂直于道路的样带,每条样带设置25个2m×2m的样方,依据样方植被调查数据计算每个样方的重要值,并利用该值进行移动窗口分析,确定道路对植物多样性的影响距离.结果表明:该区道路对植物多样性的影响距离为20～34m,且呼林主路、运材主线和运材支线之间无显著区别.道路影响距离内灌木层和草本层的植物多样性大于森林内部生境,Shannon-Weiner指数分别增加21%和60%,灌木层对道路影响的反应比草本层更加稳定,而乔木层没有显著变化.草本植物柳兰(Chamaenerion angustifolium)是路域植被的特征物种.以该影响距离为基础估算,2000年呼中林业局和黑龙江大兴安岭林区道路占地面积均约为0.10%,对植被的影响面积分别为1.70%和1.53%.

Forest road has far-reaching effects on plant species diversity across varying scales,and the estimation of its effect distance and effect zone is a key issue to integrate the road effect and ecological processes in forest area. In this paper,ten transects,2 m wide and extending 50 m from varying grade roads including main road,main line for wood transportation,and secondary line for wood transportation in Huzhong forest area of Great Hing＇an Mountains were set. The plant composition was investigated in twenty-five 2 m×2 m plots of each transect. The road-effect distance on plant species diversity identified by moving window analysis in terms of the important value of each plot. The results showed that in study area,the effect distance reached up to 20-34 m,regardeless of the roads grade. The plant species diversity of shrub stratum and herb stratum within the effect zone was greater than that in adjacent habitat,with the Shannon-Weiner index increased by 21% and 60%,respectively. The response of shrub stratum to the road effect was more stable than herb stratum,but no significant change was observed in tree stratum. Chamaenerion angustifolium was the indicative species of road-effect zone communities. Based on the estimation of road-effect distance,the road area in Huzhong Forestry Bureau and Great Hing＇an Mountains occupied about 0.10%,and its effect zone on vegetation occupied 1.79% and 1.53%,respectively.