九连山亚热带常绿阔叶林群落特征研究

Characteristics of a Subtropical Evergreen Broad-leaved Forest Community in Jiulianshan

于2008年在九连山保护区建立4 hm2固定监测样地,调查样地内胸径(DBH)≥1 cm的个体,以了解该区域的群落学特征。结果表明,群落的区系组成热带成分比较多,总体上呈现亚热带向热带过渡的区系特征。样地内共有植物58科、107属、221种,物种数和个体数较多的科为山茶科、樟科和壳斗科。群落稀有种较多,所占比例为40.72%。群落以红钩栲(Castanopsis lamontii)、米槠栲(C.carlesii)、罗浮柿(Diospyros morrisiana)、细枝柃(Euryaloquaiana)、罗浮栲(C.fabri)和丝栗栲(C.fargesii)为主要优势种。垂直结构由乔木上层(≥18 m)、乔木中层(10～18 m)、乔木下层(5～10 m)、灌木层(<5 m)、草本层组成。样地内所有个体的径级分布呈现倒"J"型,表现群落的稳定与正常生长状态。红钩栲、米槠、罗浮柿、罗浮栲、木荷(Schi ma superba)、鸭公树(Neolitsea chuii)、红楠(Machilus thunbergii)和黄丹木姜子(Litsea elongata)呈现倒"J"型,种群稳定且处于正常增长状态。样地内未发现DBH≤15 cm的马尾松(Pinus massoniana)个体,该种群属于衰退型。九连山常绿阔叶林样地优势种在不同尺度和不同径级范围内以聚集分布为主。随着研究尺度的增加,不同物种聚集程度表现出不同的变化趋势。

The subtropical evergreen broadleaved forest in Jiulianshan is a transitional type between the mid-subtropical and lower subtropical forest types.The species are abundant.To understand the particular characteristics of the local forest community,a 4 hm2 permanent experimental field plot was established.Trees with a DBH of at least 1 centimeter were mapped and measured.The results of an analysis are presented in this paper.The floristic characteristics indicate that the tropical element is more dominant than the temperate one.As a whole,the floristic composition is a transitional one between subtropical and tropical regions.A total of 221 species,belonging to 107 genera and 58 families is found in the plot.The greatest number of species and individuals belongs to the families Theaceae,Lauraceae and Fagaceae.The proportion of rare species is high,accounting for 40.72% of the total number of species.Based on the importance value,Castanopsis lamontii,C.carlesii,Diospyros morrisiana,Eurya loquaiana,C.fabri and C.fargesii are dominant species.The vertical structure is composed of an upper tree layer（≥18 m）,a middle tree layer（10～18 m）,a lower tree layer（5～10 m）,a shrub layer（5 m）and a herb layer.The DBH distribution of all individuals has an inverted-J shape,which indicates a stable and normal size structure.Castanopsis lamontii,C.carlesii,D.morrisiana,C.fabri,Schima superba,Neolitsea chuii,Machilus thunbergii and Litsea elongata communities appear to be stable with an inverted-J shaped distribution.Pinus massoniana belongs to the decreasing community without the individual with DBH below 15 cm in the plot,and the dominant species tend to have an aggregated spatial distribution in different DBH classes and at different scales.The spatial aggregation degrees of different species show different changing trend with the increasing scale.