Study On Population Dynamics And Structure Characteristics Of Alnus Sibirica In Changbai Mountain

In order to preliminary research and discuss the population dynamics and structure characteristics of Alnus sibirica in Changbai Mountain, the method of spatial series substituting for time series had been used to analysis the composition of species, size structure, static life table, the spatial distribution pattern and other indicators, the main results were as follows:(1)There were a variety of plants of Alnus sibirica community in Changbai Mountain. Community stratification phenomenon was obvious. Phanerophytes and geophytes were main components of Alnus sibirica community, but therophytes were less. Look from the floristic composition, in addition to the world distribution, the main distribution type was temperate distribution family, and they were respectively account for 34.15%, 29.17%.(2) The size class distribution fitting was subject to normal distribution. With the increasing average diameter, the peak of the curve moved to the large diameter class. The size structures of the population was influenced by community type, population density and growth. The results showed that: In the survey areas, with the changing community’s environment and the invasion of the neutral and shadow resistance species, community succession tended to be deciduous broad-leaved forests. The Alnus sibirica’s DBH growth was influenced by population density. Population density and average DBH showed a negative correlation relationship. As the growth process of Alnus sibirica, the population would gradually showed the characteristics of the insufficient reserve forces, because of the limited resources which leaded to the competitions between and within populations.(3) The age structure of Alnus sibirica population was normal distribution. Population fluctuation was very apparent. Thinking of the future external environment disturbance, the population would tend to decline. Survival curve tended to Deevey-Ⅱ. Mortality rate and vanishing rate curve were almost the same change trend. Survival functional rate showed that the characteristics of Alnus sibirica population were Early volatility, medium-term stability and Post-recession. With the increasing age, time series analysis showed that the number of young class population had gradually reduced and the number of age and older had grown.(4) The spatial distribution pattern of Alnus sibirica populations in different communities was cluster or random distribution. In the different growth stage, the spatial distribution pattern of individual group was different. As the growth of the population age, the spatial distribution was from cluster distribution to random distribution.