亚热带常绿阔叶混交林幼苗天然更新及其空间分布

Natural Regeneration Characteristics and Spatial Distribution Pattern of Subtropical Evergreen Temperate Broad-leaved Mixed Forest Seedling

为了探索亚热带常绿阔叶混交林天然更新特征以及研究种群在幼苗阶段的空间分布格局,以流溪河国家森林公园为研究对象,基于10块样地森林天然更新幼苗的调查数据,根据国家森林资源连续清查技术规定,将幼苗划分为3个更新等级:Ⅰ级,株高<0.3 m;Ⅱ级,0.3 m≤株高<0.5 m;Ⅲ级,株高≥0.5 m且胸径<1.0 cm,研究阔叶混交林林分幼苗天然更新特征,采用7种聚集度指数判定幼苗空间分布格局。结果表明:阔叶混交林天然更新幼苗总共有26科39属58种,数量占比前三的依次为罗浮锥Castanopsis faberi、华润楠Machilus nanmu、木荷Schima superba;阔叶混交林林分及各主要树种更新幼苗密度随天然更新质量等级增大而减小;所有幼苗的更新质量均不佳;各树种幼苗空间分布格局均呈聚集分布,不同树种幼苗聚集强度不同,其中豺皮樟Litsea rotundifolia var.oblongifolia聚集强度最强,竹叶木姜子Litsea pseudoelongata最弱。流溪河国家森林公园常绿落叶阔叶混交林主要树种的更新幼苗空间格局均呈聚集分布;罗浮锥幼苗更适合在郁闭度大的林下环境中生长;阔叶混交林林分较大的郁闭度以及林下灌木限制了林下幼苗的更新。

To explore the characteristics of the natural regeneration of subtropical evergreen broad-leaved mixed forest and the spatial distribution patterns of the population in the seedling stage,Liuxihe National Forestry Park was taken as the research object.Based on the survey data of natural regeneration seedlings in 10 plots,the seedlings were divided into three regeneration levels according to the technical regulations of the National Forest Resources Continuous Inventory,the seedlings were divided into three regeneration grades:Grade I,plant height<0.3 m;Grade II,0.3 m≤plant height<0.5 m;Grade III,plant height≥0.5 m and DBH<1.0 cm.To study the natural regeneration characteristics of broad-leaved mixed forest seedlings,and seven aggregation indices were used to determine the spatial distribution patterns of seedlings.The results showed that there were 58 species of natural regeneration seedlings belonging to 39 genera and 26 families in the broad-leaved mixed forest.The top three species were Castanopsis faberi,Machilus nanmu,and Schima superba.The regeneration seedling density of the broad-leaved mixed forest and the main tree species decreased with the increase of natural regeneration quality grade.The regeneration quality of all seedlings was poor.The spatial distribution pattern of seedlings of all tree species showed aggregation distribution,and the aggregation intensity of seedlings of different tree species was different.Among them,the Litsea rotundifolia var.oblongifolia was the strongest,and that of Litsea pseudoelongata was the weakest.The spatial pattern of regeneration seedlings of the main tree species in the evergreen and deciduous broad-leaved mixed forest in Liuxihe National Forest Park showed an aggregated distribution.In this survey,the Castanopsis faberi seedlings were more suitable to grow in the understory environment with high canopy density.The large canopy density of broad-leaved mixed forest and understory shrubs limited the regeneration of the understory seedlings.