濒危植物厚叶木莲的群落学特征及其保护

THE COMMUNITY CHARACTERISTICS AND CONSERVATION STRATEGIES OF ENDANGERED SPECIES MANGLIETIA PACHYPHYLLA

摘要:

根据从化三角山次生常绿阔叶林的样方调查结果，分析了中国特有植物厚叶木莲（ManglietiapachyphyllaChang）的天然分布特点，分布区的自然环境概况，群落的区系特点，群落学特征及其保护策略．厚叶木莲仅零散分布于广东从化三角山、龙门南昆山和新丰小沙罗等地海拔650－1000m的常绿阔叶林中，分布区非常狭窄．在1200m²的样地里有维管植物132种，隶属于57科89属。Shannon－Wiener物种多样性指数为5．45，均匀度为84．39％，类似于其他类群的南亚热带常绿阔叶林，但较低于海南的热带雨林类群．本群落植物区系的分布类型是以泛热带分布和热带亚洲分布两大类为主，热带－亚热带区系植物成分在本群落中占有明显的优势，其区系特点具有从热带向亚热带过渡的性质．该群落命名为赤楠、假轮叶虎皮楠、厚叶木莲群落，可分为乔木层（2亚层）、灌木层及草本层等层次．本群落以中、小高位芽植物占优势，缺乏大高位芽、地面芽和一年生植物，叶型以中型叶为主．种群分布格局分析表明，大部分优势种呈集群分布，其中厚叶木莲呈集群分布。种群的立木结构分析表明，厚叶木莲种群已处于衰退模式，有即将在群落中消失的可能，属于濒危物种，应加以保护，对厚叶木莲及其群落的保护应立足于就地保护。

Abstract:

Based on the vegetation survey on a secondary evergreen broad-leaf forest atSanjiaoshan, Conghua, near Guangzhou, the natural distribution characteristics,environmental condition, floristic composition and community characteristics of China'sendemic species Manglietia pachyphylla Chang and its conservation strategies were studied in June, 1997. The results indicated that Manglietia pachyphylla was naturally distributed inthe secondary evergreen broad-leaf forest at altitudes from 650 to 1 000 metres in a narrow zone．There were 132 species of vascular plant in 89 genera of 57 families in plots of 1 200 m². The diversity index and evenness of the tree and shrub species in the community were 5.45 and 84.39％，respectively，which were similar to those of other evergreen broad-leaf forest in the neighboring regions， but lower than those in tropical rain forest in Hainan. The floristic composition of the community showed a transitional characteristics of tropical and subtropical elements．The community was termed as Syzygium buxifolium + Daphniphyllum subverticillatum + Manglietia pachyphylla Community．It can be vertically divided into three layers，tree (with 2 sublayers)，shrub，and grass layers．There were many species in the tree layer and shrub layer， but few species in the grass layer．The dominant species of Magnoliaceae in tree layer were found to be Manglietia pachyphytta and Michelia maudiae. The mesophanerophytes and microphanerophytes made up high percentage，and the megaphanerophytes，Hemicryptophytes and therophytes were not found in the species life form spectrum of the community．The mesophyll also made up high percentage in leaf-size class spectrum of the community．The distribution pattern of magnoliaccous plants were measured by variance／means ratio．and the result indicated that most of the dominant species were clumped in distribution，Manglietia pachyphylla and Michelia skinnerana were clumped，and Michelia maudiae was random．Analysis on structure of magnoliaceous populations indicated that Michelia maudiae and Michetia skinnriana were at the stable stage，but Mangtietia pachyphylla expressed a decline tendency．Therefore，Manglietia pachyphylla is an endalagered species which must be preserved through in situ and ex situ conservation，and the preservation strategies should be centred on in, situ conservation.