蛇足石杉的种群结构和致危因素

摘要

本研究通过对中国主要分布区的蛇足石杉天然种群进行生态调查,分析导致该物种资源骤减的主要原因,以找出合理的保护措施.我们调查了江西、贵州、广西、重庆及海南等5个省区蛇足石杉天然居群,分析了该物种的种群结构、变化趋势及生长速率等.结果表明调查样地的蛇足石杉居群结构相似,幼苗和幼株为居群的主要构成,成株相对较少;尽管不同样地的蛇足石杉生长速率存在差异,但年生长量均在2.0 ～3.0 em之间.从繁育方式看,海南居群芽胞幼苗和可产生芽胞的成株占居群的比例分别为80.5％,19.1％,均显著高于其它居群,这揭示了海南种群更新以芽胞繁殖为主,而其它居群以孢子繁殖为主.该调查结果表明导致蛇足石杉资源减少的内在因素在于:芽胞幼苗生长速率快而芽胞数量少、孢子存在长时间休眠且萌发困难、植株生长缓慢;外在因素在于过度采集和生态环境遭遇严重破坏等.对此我们提出了多种保护方法,在保护好生态环境和现有资源的基础上进行繁育研究,通过野生抚育防止种群萎缩.%Our study objectives were to elucidate the structures and the main renewal patterns of different Huperzia serrata populations in China and find some methods to protect the wild resource of this species.Otherwise,the optimal reproduction pattern of protecting the wild resources and plantation would be adopted in the future.In 2011,we investigated the populations in five fields of five provinces in China in order to ascertain the population structures,seedling origin,habitat factors,the reason of resources shrinking and others.The five provinces included Guangxi,Chongqing,Guizhou,Jiangxi and Hainan.In each field,25 ～63 quadrates were set up randomly.According to the investigation results,we analyzed the reasons why resources of H.serrata were acceleratedly reducing,and the main renewal patterns were confirmed by comparing the sporeling propagations and gemmling's in a populations.The factors those caused the wild resources to be shrinking were as following:low growth speed,spore dormancy,environment changing,destroyed habitat,extensive collection and so on.The plants grew 2 ～ 3 cm annually,and the spores spent several years to germinate.Besides,HN population had the different primary renewal pattern with other populations,and this was attested by the next data.The gemmlings accounted for 80.5％ and the adult plants produced gemmaeaccounted for 19.1％ in all plants of Hainan population.While in other populations,the proportions were lower significantly.Therefore,reproduce via gemmae was the main renewal pattern in Hainan population,while others were via spores.So the wild resources could be protected by cultivating gemmae.Besides,the other measures of protecting the resources should be carried out,such as studying on the technology of reproduction,reducing collection,protecting the wild habitat and others.