华石斛种群动态与繁殖策略的相关性分析

Correlation Analysis Between Population Dynamics and Reproduction Strategies in Dendrobium sinense(Orchidaceae),an Endemic Orchid in Hainan Island

根据中国海南特有兰花种华石斛(Dendrobium sinense)的生物学特征调查和种群监测观察,计算其各龄级的存活数、出现频率和子代数,描述其繁殖行为和机制;根据不同龄级植株存活数及平均子代数编制种群静态生命表和生殖力表、绘制存活曲线和年龄锥体,并构建Leslie矩阵模型对种群数量动态过程进行预测;根据物候特征和克隆生长观察,分析生殖行为和繁殖策略,并研究种群数量动态与生殖行为及年龄锥体之间的关系。结果表明,华石斛的种群年龄锥体属于壶型锥体,种群存活表现为Deevey I型;种群的净增长率、内禀增长率和周限增长率较低,属于衰退型种群,这与Leslie矩阵模型对种群的预测结果相似。华石斛的生殖行为兼具无性繁殖和有性繁殖,无性繁殖不增加种群的个体数量,可延续基株的寿命以维持种群数量,并为有性繁殖积累营养。华石斛平均开花和结实率仅为19.38%和25.61%,外加且幼苗萌发困难的局限性,致使华石斛幼苗补充严重不足,因此,华石斛的迁地保护和组培苗野外驯化迫在眉睫。

Analysis of population dynamics has rarely been used in orchids in China. According to the investigation of biological characteristics of and the population monitoring of Dendrobium sinense, an endemic orchid in Hainan, the survival number in each age-class, the emergence frequency and the number of filial generations of D. sinense were computed, and the reproductive behavior and mechanisms of D. sinense were described. The population static life table and fecundity table as well as the survival curve and age pyramid were prepared based on the survival number in each age class and the number of filial generations, and a Leslie matrix model were established to predict the numeric dynamics of the populations. Reproductive behavior and breeding strategy were analyzed based on the observation ofphenological characteristics and clonal growth of D. sinense. The relationship of the numeric dynamics of the populations of D. sinense with its reproductive behavior and its age pyramid were analyzed. Results showed that the age pyramid was kettle-shaped and that the survival performance of populations was similar to that of Deevey type I. The net reproduction rate, the intrinsic increase rate and the finite increase rate of D. sinense were very low, which indicates that the populations were in decline, which was similar to the prediction by Leslie matrix model.Reproductive behavior of D. sinense included both sexual reproduction and clonal growth. Clonal growth could increase the number of individuals prolong the life of individuals, maintain the populations and accumulate nutrients for sexual reproduction. The average flowering and seed setting rates were 19.38% and 25.61%,respectively, and seed germination of D. sinense were limited, causing serious shortage in supply of seedlings of D. sinense. Therefore, it is imperative to conduct ex situ conservation and field domestication of tissue cultured seedlings of D. sinense.