浙江六十田自然保护小区常绿阔叶林群落特征及优势乔木种的动态

The community features of evergreen broad-leaved forest and the population dynamics of dominant species in Liushitian Nature Reserve of Zhejiang Province

对浙江省磐安县六十田省级自然保护小区常绿阔叶林的群落结构特征及其主要乔木树种的种群动态进行了调查研究.根据各树种的重要值判断,该地区常绿阔叶林的主要乔木组成种为东南石栎(Lithocarpusharlandii)、红楠(Machilus thunbergii)、木荷(Schima superba)、米槠(Castanopsis carlesii)、青冈(Cyclobalanopsisglauca)、紫楠(Phoebe sheareri)和华东楠(Machilus leptophylla),其中东南石栎和木荷为主要优势种.群落中乔木层、灌木层、草本层及藤本的物种丰富度、多样性、均匀度都偏低,优势度相对较高;其生活型以包括藤本在内的高位芽植物占绝对优势,达85.45%;叶级以中型叶为主(占61.82%),小型叶次之(占29.09%);叶型以单叶占有较大的优势,达到89.09%;叶质以革质叶占优势(56.36%),纸质叶次之(40.00%).生活型及叶的特征表明该群落属于中亚热带常绿阔叶林.群落中主要乔木树种水平结构整体上呈均匀分布状态,说明群落中种内和种间竞争激烈.依据胸径级别频率分布的形状,7个主要组成种的种群结构可以大致归纳为:倒金字塔型、倒“J”型、纺锤型和双峰型.其中,种群结构呈倒金字塔型的东南石栎、米槠、青冈和紫楠及呈纺锤型的华东楠,因为缺乏幼苗和幼树,在演替过程中种群将衰退;而呈双峰型的红楠和呈倒“J”型的木荷,因有较为丰富的幼苗储备而将成为该群落的优势种.

Broad-leaved evergreen forest is a zonal vegetation type and an important part of land ecosystems in subtropics of the world. Based on the data collected from sample plots, the species composition, physiognomy of the community, the spatial distribution and population structure of the dominant species in the evergreen broad-leaved forest in Liushitian Natural Reserve of Zhejiang Province were analysed. The results showed that there were 7 dominant species： Lithocarpus harlandii, Machilus thunbergii, Schima superba, Cyclobalanopsis glauca, Castanopsis carlesii, Phoebe sheareri and Machilus leptophylla, in the evergreen broad-leaved forest in term of the importance value of species. P. brevicaudata and S. superba were the major dominant species in the community. The richness index, biodiversity index and evenness index were on the low side, except ecological dominance index. Phanerophytes occupied a dominant position in the community with a percentage was 85.45% among all life forms; the dominant leaf size was mesophyll whose percentage was 61.82%, followed by microphyll （ 29.09% ） ; single leaves were dominant in leaf form and the percentage of those was 89.09%. Researches showed that this community belonges to mid-subtropical evergreen broad-leaved forest. Because of intra-specific and inter-specific competition, the spatial patterns of the major species in the forest conformed to a random distribution. The population structures of the dominant species were categorized into four regeneration types： inverse pyramid-shaped, inverse J-shaped, spindle-shaped and double peak-shaped, based on their diameter at breast height （ DBH） frequency distribution patterns. The species that belong to the inverse pyramid- shaped and spindle-shaped would be in decline due to lack of seedlings. M. thunbergii and Schima superba, which had abundant seedlings, would be dominant species in the future.