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

Key words: 
• Dendrobium sinense /
• population dynamics /
• reproductive allocation /
• endemic to Hainan

Abstract: 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.