Characteristics of age structure of modules on Leymus chinensis populations inseveral succession series in degradation L. chinensis community

The modular populations on Leymus chinensis in different succession series in enclosed and cutting glassland in the Songnen Plains, Northeast China was studied. The experiment also analysed its age structure of tillers, rhizome length, bud bank and the composition of dormancy modules in different succession series by using statistical methods of ANOVA. The results of this study showed that the age structure of tillers in different succession series displayed an increasing age structure, representing 1 a2 a3 a. Rhizome total length was an important indicator which reflected the capacity of asexual reproduction and space to expand. It was constructed by four age classes. The greatest age class of rhizome total length was 2 a in different succession series and the structure of rhizome total length was related to age structure of tillers.The population had a vigorous vegetative reproduction during the late period of growing season. The age spectrum of bud bank in different plots in October was 0 a1 a2 a3 a, representing an increasing age structure.It could accurately be forecasted that the population in next year would still be an increasing age structure by the number of bud bank. During the late period of growing season, the L. chinensis populations produced two vegetative forms on dormancy module, the infinite buds and dormancy seedlings, which was considered as the potential population on the next year. The dormancy seedling stock in cutting glassland was significant higher than that in enclosed glassland because cutting glass could promote the formation of dormancy buds and seedlings. The capacity of vegetative propagation of L. chinensis rhizome was senior to that of tillering node. It could be forecasted that the populations in different succession series would represent an increasing age structure in next year. However, the proportion of winterness and springness stems in enclosed glassland would be different from that in cutting glassland. The characteristics of age structure of population modules could reflect the trend of population development.