野生仙湖苏铁群落特征研究

Community characteristics of Cycas fairylakea , an endemic and endangered species.

在样方调查的基础上,对首次在深圳塘朗山发现的野生仙湖苏铁群落进行了研究.研究表明,该群落属于南亚热带次生性常绿阔叶林,群落平均高度约9m,整个群落物种丰富度指数为226,Shannon_Wiener指数为4198,均匀度指数为0784,生态优势度为0027,3个层次多样性格局为“灌木层>草本层>乔木层”.中生性种群主要为集群分布,阳生性种群主要为随机分布.种间联结关系弱.6个优势种群中,假苹婆和鸭脚木种群为增长种群,银柴等为相对稳定种群,仙湖苏铁为衰退种群.目前仙湖苏铁群落处于演替发育过程中,促进群落向着顺向演替方向发展,恢复仙湖苏铁赖以生存的森林环境,是保护仙湖苏铁种群的有力措施.

A population of wild Cycas plants was discovered in November of 1999 in Nanshan District, Shenzhen City. The specimen was identified to be Cycas fairylakea D.Y. Wang. The total number of individual C. fairylakea plants was less than 2 000 . Thus, it is an endangered species according to the new criteria of IUCN Red Categories. The study of community characteristics of C. fairylakea was conducted based on field data. The C. fairylakea community belongs to south subtropical secondary evergreen broad_leaved forest with the average height of 9 m. The species diversity of the community is relatively high with the species richness of 226 in 4 700 m 2 , the Shannon_Wiener index of 4 198, the evenness index of 0 784 and the ecological dominance of 0 027 The diversity pattern from maximum to minimum is shrub, herb, and tree layer in three layers of the community. The spatial distribution pattern in mesophytic populations appears mostly clumped and that of heliophilic ones is mostly random as a result of their reproduction characteristics and the difference of micro_habits. A weak inter_specific association is clarified, and it shows an unsteady community structure. Among six dominant populations, populations of Sterculia lanceolata and Schefflera octophylla are increasing, and those of Aporosa dioica , Itea chinensis, and Acronychia pedunculata are relatively stable, whereas the population of C. fairylakea is declining according to their age structures. The community is still in succession process and has not reached the climax. The current situation of C. fairylakea community suggests that the necessary methods,such as “land closure for reforestation” and “no land reclaiming for plant fruits”, should be taken as soon as possible to restore the C. fairylakea community and to develop progressive succession of the community.