西双版纳“龙山”片断雨林蕨类植物的变化研究

通过对曼养广“龙山”片断热带雨林蕨类植物的调查及与３８年前的调查材料进行比较研究，初步阐明了“龙山”林中蕨类植物在科、属、种及种群等方面的一些变化。经过３８年后，“龙山”林中的蕨类植物在科、属、种的组成数量上没有发生明显的变化，仅减少了一个科，属数不变，种数由３５种增加到３８种。“龙山”林蕨类植物的组成成分却发生了明显的变化，其科的消失率和新增率分别为１１．７６％和５．８８％，即消失了２个科和新增了１个科；属的消失率与新增率均是２０．００％，分别消失了５个属和新增加了５个属；而种消失了１４个，新增了１７个，消失率和新增率分别为４０．００％和４８．５７％。种群的变化趋势是阴湿或喜阴湿的蕨种的种群趋于减少，而林缘和林窗阳性或喜阳性的蕨种的种群趋于增大。

THE CHANGING OF FERN DIVERSITY FROM THE FRAGMENT RAIN FOREST ON A HOLY HILL IN XISHUANGBANNA

Based on comparison of data of ferns obtained separately in 1959 and 1997 from the fragment tropical rainforest on the holy hill of Manyangguang in Jinghong County in Xishuangbanna,the changing of fern diversity was studied.Through the time between the year 1959 and 1997,the numbers of fern family,genus and species in the fragment forest have not showed conspicuous change,but their composition (floristic elements) have changed a lot.Among 35 species,25 genera and 17 family record in the year 1959,14 species,5 genera and 2 families have not be seen in the investigation in 1997.They are conjectured having disappeared .Among 38 species,25 genera and 16 families of ferns recorded in 1997,17 species,5 genera and 1 family were new in the fragment forest and they are conjectured appearing after 1959.The disappeared species were mainly,shade tolerant species,while the new increasing ones were mainly heliophyte.In population composition,heliophytes increased and shade tolerant decreased with forest fragmentation.