濒危植物银杉的群落特征及其演替趋势

银杉（Ｃａｔｈａｙａａｒｇｙｒｏｐｈｙｌａ）群落的外貌主要由具革质细型叶的常绿针叶中高位芽植物和具革质小、中型叶的常绿阔叶小、中高位芽植物所决定。其结构一般分为乔木层、灌木层和草本层，在有些群落内草本层不发育。组成银杉群落的高等植物有２３９种，半数以上的种类集中在杜鹃花科（Ｅｒｉｃａｃｅａｅ）等９个科中。群落中热带型属的比重低于温带型属的比重，说明银杉群落虽然分布于亚热带，却具有较强的温带分布类型的性质。现有银杉群落处在演替系列的针叶混交林和针阔混交林两个阶段，过度干扰可能使针叶混交林逆向演替到灌丛阶段；处在针阔混交林阶段的银杉群落是相对稳定的亚顶极，将维持相当长的时期，但随着土壤条件的不断改善，有向阔叶群落演替的趋势。

CHARACTERISTICS AND SUCCESSION OF THE COMMUNITIES OF CATHAYA ARGYROPHYLLA, AN ENDANGERED PLANT

The appearence of Cathaya argyrophylla communities was characterized by the evergreen coniferous mesophanerophytes with coriaceous nanophylls and the evergreen broadleaved micro and meso phancrophytes with coriaccous micro and mcso phylls.The structure of the communities was gernerally composed by tree layer,shrub layer and herb layer,but sometimes the herb layer was not developed.239 higher plant species were found in the communities,and more than 50% of them belonged to the 9 families such as Ericaceae,Fagaceae,Lauraceae etc..The percentage of tropical genera was less than that of temperate genera,which showed that the communities featured much more temperate nature though they were distributed in subtropical zone.The communities were in the stages of mixed conifers which might success to shrubs under exessive disturbance and mixed coniferous broadleaved forests which were the relatively stable subclimax.