内蒙古罕山次生林北段森林死亡梯度下植物多样性特征

Undergrowth plant diversity in the northern part of secondary forest in Hanshan Mountain,Inner Mongolia

【目的】青山保护区是内蒙古罕山次生林北段的典型区域,了解内蒙古罕山次生林北段森林死亡梯度下植物多样性特征,为科学保护和利用森林自生植物群落,探索更适宜森林发展的植物群落提供依据。【方法】以青山保护区山杨Populus davidiana次生林为研究对象,采用样地调查法对不同死亡梯度林下植物组成进行调查,使用生物多样性指数和群落相似系数对植物组成及多样性的差异进行分析。【结果】内蒙古罕山次生林区北段不同死亡梯度下样地植物有45种,其中,乔木9种,灌木5种,草本31种,样地内的植物物种数从大到小依次为轻度死亡样地、重度死亡样地、中度死亡样地。不同样地内的Simpson和Shannon-Wiener指数从大到小依次为轻度死亡林分、重度死亡林分、中度死亡林分。中度死亡样地的丰富度指数和Pielou均匀度指数最高。通过主坐标分析(PCoA)发现轻度死亡样地内的群落差异最大。Sorensen群落相似系数(SI)为55%-61%,不同死亡梯度林分内共有种为13种,乔木层和灌木层对SI的差异影响并不大,草本多样性的降低效益明显,导致不同死亡梯度林分SI差异变大。总体而言,随着山杨死亡程度的增加植被组成差异性也不断增加。【结论】森林死亡导致植物多样性总体趋于降低,森林大量死亡抑制了草本植物多样性,但是促进了乔木和灌木的更新。研究区山杨优势度出现衰退,林内更新能否形成混交林有待进一步研究。

[Objective]Qingshan Reserve is a typical area in the northern section of the secondary forest in Hanshan,Inner Mongolia,in order to understand the characteristics of plant diversity under the forest death gradient in the northern section of the Hanshan secondary forest in Inner Mongolia,and to provide a basis for scientific protection and utilization of forest autogenous plant communities and explore plant communities more suitable for forest development.[Method]Taking the secondary forest of Populus davidiana in Qingshan Reserve as the research object,the plant composition of different dead gradients was investigated by sample survey method,and the differences in plant composition and diversity were analyzed by using biodiversity index and community similarity coefficient.[Result]There were 45 plant species in the northern section of Hanshan secondary forest area,Inner Mongolia,including 9 species of trees,5 species of shrubs and 31 species of herbs,and the number of plant species in the sample plot was as follows:mild death plot>severe death plot>moderate death plot.The Simpson and Shannon-Wiener indices in the same field showed mildly dead stands>severely dead stands>moderately dead stands.Moderately dead plots had the highest richness and Pielou uniformity index.The greatest variation in communities within mildly fatal plots was found by PCoA analysis.The SI index was in the range of 55%−61%,there were 13 species in different death gradient forest stands,the difference between the relative coefficient of the tree layer and the shrub layer was not large,and the reduction benefit of herbaceous diversity was obvious,resulting in the difference of SI index of different death gradient forest stands became larger,and overall,with the increase of aspen mortality degree,the difference in vegetation composition also increased.[Conclusion]The mass forest mortality inhibits the development of herbaceous plant diversity,but promotes the renewal of trees and shrubs.The dominance of aspen in the study area declined,and whether the diversity of forest renewal could form mixed forests needed to be further studied.