内蒙古大兴安岭南段森林死亡对植物多样性的影响

Effects of Forest Mortality on Plant Diversity in the Southern of Great Xing'an Mountains,Inner Mongolia

【目的】为了解内蒙古大兴安岭南段森林大面积非正常死亡对森林植物多样性的影响。【方法】以内蒙古大兴安岭南段赛罕乌拉保护区杨桦次生林为研究对象。通过调查森林死亡后不同死亡梯度的林下植被组成,用生物多样性指数和群落相似系数对林下物种组成及多样性的差异进行分析。【结果】研究发现:内蒙古赛罕乌拉保护区森林死亡后样地内共调查发现植物物种63种,其中乔木4种、灌木9种、草本50种,对照样地物种最多,群落物种多样性与森林死亡后枯落物厚度、粗木质残体密度呈显著负相关;森林死亡后倒木样地对物种丰富度、Shannon-Wiener指数、Simpson指数的贡献最大。群落乔灌草不同层次物种多样性对森林死亡的响应差异明显。SI指数在32%~72.91%范围内,不同死亡梯度样地内共有种为23种,草本多样性导致不同死亡梯度样地SI指数差异变大。【结论】研究结果表明森林死亡对物种多样性瞬时影响较大,但随森林死亡时间的推移,乔木层多样性指数逐步增加,灌木层多样性指数先下降再升高,而草本层却随着死亡梯度多样性指数下降,所以森林大量死亡抑制草本植物多样性的发展,但是对于乔木和灌木起到促进更新的作用。研究区山杨优势度出现衰退,林内更新的多样性能否形成混交林有待进一步研究,研究结论对退化生态系统及生物多样性的保护与恢复具有重要参考意义。

【Objective】This paper aims to understand the impact of large area abnormal forest death on forest plant diversity in the southern section of the Greater Xing'an Mountains in Inner Mongolia.【Method】The poplar and birch secondary forests in the Saihanwula Nature Reserve in the southern section of the Great Xing'an Mountains in Inner Mongolia were taken as the research object.Through investigating the composition of undergrowth vegetation composition with different death gradients after forest death,the differences in undergrowth species composition and diversity were analyzed by using biodiversity indices and community similarity coefficients.【Result】The results showed that 63 species of plants were found in the forest after forest death in Saihanwula Nature Reserve,including 4 species of trees,9 species of shrubs,and 50 species of herbs.The control forest had the most species.The community species diversity was significantly negatively correlated with the thickness of litter and the density of coarse wood residues after forest death.After forest death,fallen wood stands contributed the most to species richness,Shannon-Wiener index,and Simpson index.The response of tree,shrub,and herb species diversity at different levels to forest death was significantly different.The SI index ranges from 32%to 72.91%,and there are 23 species in different death gradient forests.Herbal diversity leads to greater differences in the SI index of different death gradient forests【.Conclusion】The results indicated that forest death has a significant instantaneous impact on species diversity,but with the passage of forest death time,the diversity index of tree layer gradually increases,while the diversity index of shrub layer first decreases and then increases,while the diversity index of herb layer decreases with the death gradient.Therefore,a large number of forest deaths inhibit the development of herb plant diversity,but play a role in promoting the regeneration of trees and shrubs.The dominance of Populus davidiana in the study area has declined,and whether the diversity of regeneration within the forest can form a mixed forest remains to be further studied.The research conclusions have important reference significance for the protection and restoration of degraded ecosystems and biodiversity.