Age Composition and Dynamic Characteristics of the Main Populations of Endangered Malus sieversii
Malus sieversii is a precious and endangered species in China.In this study,the sample plots of M.sieversii were delimited at the typical sites including Nazi (NZ),Mohuer (MH),Narat (NRT) and Jiaotuohai (JTH) in the Ili River Valley so as to investigate the age composition and population status of M.sieversii,make the static life table,and carry out the survival analysis.The time series analysis was used to predict the population trend.The study results could provide the theoretical information for protecting M.sieversii.The results showed that the proportion of young trees was low,and that of middle-aged and old trees was high.The average age in NZ was older,and that in JTH was younger.Compared with others,the population in MH was more sensitive to environment disturbance.The number of survivors,total individual number and life expectation of the population were lower in NRT than in other places.The population in NRT decreased early with high elimination rate.The survival curve appeared to approach the Deevey-Ⅱ type,which indicated that the mortality rate of the trees with different ages was similar.With the age increase,the mortality density curve decreased firstly and then increased.The hazard rate increased obviously after age class Ⅳ,which indicated that the effect of environment pressure on M.sieversii was significant after age class Ⅳ.Because of the disturbance from grazing,tourist activities and insect pests,it was predicted with the time series analysis that the proportion of old trees increased with the decrease of the proportion of young and middle-aged individuals.It was suggested that the protection of M.sieversii resources should be strengthened by a series of measures,such as artificially increasing the number of seedlings,regulating the forest density,strictly preventing and controlling plant diseases and insect pests,and protecting the core areas to relieve the contradiction between forestry and grazing.
Malus sieversiipopulationage classstatic life tablesurvival analysistime series
国家科技期刊平台
NSTL
万方数据
维普
