不同间伐强度对自然保护区人工林植被多样性及分布格局的影响——以河北省塞罕坝机械林场为例

Effects of tending thinning on the vegetation diversity and distribution pattern of artificial forests in nature reserves:a case study of Saihanba Mechanical Forest Farm in Hebei Province

【目的】研究自然保护区抚育间伐强度对物种多样性及空间分布格局的影响规律,对于自然保护区生物多样性保护和稳定性的提高具有重要意义。【方法】以塞罕坝自然保护区华北落叶松Larix principis-rupprechtii和樟子松Pinus sylvestris mongolica人工林为研究对象,分别设置高(61%)、中(48%)、低(36%)3种间伐强度固定样地18块以及6块未间伐对照样地,调查样地林分因子和林内草本和木本植物种类、数量、基径和分布信息。基于调查数据,计算物种多样性指数(Simpson指数、Shannon-Weiner指数、Pielou均匀度指数、物种丰富度),同时运用双相关函数g(r)与g_(12)(r)计算分析木本植物空间格局。【结果】华北落叶松高间伐强度样地草本植物物种种类较对照样地增加了13%,中间伐强度样地减少了15%,低间伐强度样地无变化,高中低间伐样地木本植物物种种类较对照样地分别减少了33%、11%、33%;樟子松高中低间伐样地草本植物物种种类较对照样地分别减少了32%、25%、20%,高间伐强度样地木本植物物种种类较对照样地增加了40%,中间伐强度样地较对照样地无变化,低间伐强度样地较对照样地减少了10%。2种林分主林层木本植物空间格局以随机分布为主,对照样地主林层木本植物在小尺度上出现聚集分布,间伐样地主林层木本植物在大尺度上出现随机分布,华北落叶松林下木本植物空间格局在高间伐强度样地出现聚集分布,樟子松林下木本植物空间格局则在对照和低间伐强度样地出现聚集分布。【结论】中高间伐强度有利于塞罕坝自然保护区生物多样性保护和林分结构的优化。

【Objective】It is of great significance to study the effect of tending thinning intensity on species diversity and spatial distribution patterns for improving the protection and stability of biodiversity in nature reserves.【Method】The Larix principisrupprechtii and Pinus sylvestris var.mongolica plantations in the Saihanba area were studied.The herbaceous and woody plants in the understory of the plantations(Larix principis-rupprechtii and Pinus sylvestris)were used as the research objects.Three sample plots with high thinning intensity(61%),medium thinning intensity(48%),low thinning intensity(36%)and 3 control plots without thinning were set up in the Larix principis-rupprechtii and Pinus sylvestris plantation.We investigated the species names,diameter at breast height(or basal diameter),distribution information,height and crown width of the herbaceous and woody plants in the understory.The species diversity indexes(Simpson index,Shannon-Weiner index,Pielou evenness index,species richness index)and the double correlation functions g(r)and g_(12)(r)were calculated to present the biodiversity,spatial patterns and interspecific correlation of the woody plants.【Result】Compared with the control plot,the species richness of the herbaceous plants in the Larix principis-rupprechtii plantation with a high thinning intensity and a medium intensity showed an increase by 13%and a reduction by 15%,and the plot of a low intensity remained unchanged.The species richness of the woody plants in the plot of a high,medium and low tending intensity decreased by 33%,11%and 33%,respectively,compared with the control plot.Compared with the control plots,the species of the herbaceous plants in the high,middle and low thinning plots of Pinus sylvestris decreased by 32%,25%and 20%,respectively.The species richness of the woody plants increased by 40%in the high thinning intensity plot,which didn’t change in the medium thinning intensity plot and decreased by 10%in the low thinning intensity plot in comparison to the control plot.The woody plants in the main storey of Larix principis-rupprechtii and Pinus sylvestris var.mongolica plantations were mainly randomly distributed.The woody plants in the main storey of the control plots showed aggregated distribution on a small scale,which were randomly distributed on a large scale in the thinning plots.The woody plants under the Larix principis-rupprechtii plantation showed aggregated distribution in the plots with a high thinning intensity,while the woody plants under the Pinus sylvestris plantation showed aggregated distribution in the low thinning intensity plots and the control plots.【Conclusion】A medium or high thinning intensity is beneficial to the conservation of biodiversity and the optimization of the stand structure in Saihanba Nature Reserve.