濒危植物海南龙血树的种群结构与动态

The population structure and dynamics of Dracaena cambodiana,an endangered tree on Hainan Island

了解种群的生存现状与动态趋势对濒危植物的保护至关重要。为了更好地保护濒危海南龙血树种群,对海南岛不同生境的11个海南龙血树(Dracaena cambodiana)种群进行了调查;并利用个体基径数据建立各种群的年龄结构和静态生命表,得到种群年龄结构动态指数,绘制种群存活曲线和生存函数曲线,从而获得海南龙血树的种群结构与动态。结果表明:海南龙血树种群年龄结构与种群所处的生境关系密切,海边的NS和YL种群结构为衰退型,LN和CH居群为稳定型,而非海边种群为增长型,没有老龄个体;11个种群中,EXL种群显示出最高的增长趋势和最好的种群稳定性,NS和YL种群稳定性最差,种群抗干扰能力极低;11个种群的存活曲线均属于Deevey-Ⅰ型,但生存函数分析显示海南龙血树种群生活史早期和晚期脆弱,中期稳定,这表明海南龙血树种群所处的生境更适合成年个体生存,现有的生境对幼龄个体的环境筛作用较强。海南龙血树属于退偿物种,针对其种群的生存现状,应采取多种方法相结合的方式进行保护与复壮。

For the protection of an endangered plant, it is very important to understand its population survival status and population dynamics. In order to better protect the rare and endangered Dracaena cambodiana, 11 populations of D. cambodiana in different habitats on Hainan Island were investigated, and the basal diameter of individuals was recorded to establish age structure and static life table, and then the population age structure dynamic index and the survival curve and survival function curve, so as to determine the population structure and survival status of D. cambodiana. The results showed that the population age structure of D. cambodiana is closely related to its habitat. Populations in habitats near sea, NS and YL, were declining, whereas those of CH and LN were stable, and the other 7 populations farther from the sea were increasing. Among these 11 populations of D. cambodiana, the EXL population showed the highest growth trend and the best stability. JFM, JF, CH, and LN populations also showed a growth trend and good stability, whereas NS and YL populations showed the worst stability and anti-interference ability. The survival curve of the 11 D. cambodiana populations were of a Deevey-I （convex curve） type, and the survival rate of young individuals was higher than that of middle-aged and aged individuals, indicating that the survival ability of young individuals is better than that of middle-aged and aged individuals. However, the results of survival function analysis showed that the early and late life history of D. cambodiana were fragile, whereas that of middle aged was stable, suggesting that the habitat of D. cambodiana was more suitable for the survival of middle-aged individuals, and that the young individuals were under strong effects of environmental filtering. D. cambodiana is a depensation species, and therefore multiple protection methods should be used to protect and rejuvenate the current populations.