| The tiller-nodes of 6 species of rhizome grass, including Leymus chinensis, Hemarthriajaponica, Arundinella hirta, Calamagrostis epigeios, C. rigidula, Hordeum brevisubulatum in Songnen Plain, can live at best for 2 to 5 years, and do 2 to 4 propagating generations which is the same as the age class of tiller in number. The age structure of population is an increasing model which the young tiller is more than the old at quantity and biomass. During the whole growing season, the age spectrum varies for each species. The 6 species of rhizome grass have lower earing percent, which in young tillers is more than the one in old tillers. The reproductive tiller is obviously higher than the vegetative, and there is little difference among all of age classes reproductive tiller at height and biomass, but the vegetative tiller is decreasing with the increasing age class. The winter tiller is more than the spring tiller at quantity hi Leymus chinensis, Calamagrostis epigeios and C. rigidula population at the beginning growing season. It is an efficient strategy to increasing survival fitness and propagating potential for rhizome grass to grow many active and strong winter tillers.The rhizome of grass, including Leymus chinensis, Hemarthria japonica, Arundinella hirta, Calamagrostis epigeios and C. ?rigidula populations, can normally live for 3 to 4 years which is the same as the age class. The age spectrum of rhizome is very changeable during the growing season. The 1st age class rhizome emerges at mid of growing season. The age structure of rhizome is an increasing model at length and weight at the end of growing season. The morphological character of rhizome is different among grass species, as well as the dry matter production, but the production in the young rhizome is more than the one in the old. The negative correlation of the dry matter production to the age class ofrhizome indicates level of significance (p<0.05, pO.Ol) in Leymus chinensis, Calamagrostis epigeios and C. rigidula populations. The changing process of rhizome growing and the propagating process of population expanding supplement each other.The stocks of bud bank is different among 6 species of rhizome grass, and changes for each species in the different period of growing season. The bud bank is composed of 3 age classes bud on Leymus chinensis , Arundinella hirta and Hordeum brevisubulatum populations, 2 age classes bud on Hemarthria japonica , Calamagrostis epigeios and C. rigidula populations. The age structure of bud is obviously an increasing model in all of 6 grass species. Bud is produced in both rhizome and tiller-node, rhizome can produce more buds than tiller-node on Hordeum brevisubulatum, Arundinella hirta, Calamagrostis epigeios, C. rigidula and Hierochloe glabra populations. Both 1st age rhizome and tiller-node of 1st age tiller are mainly two contributors in importing of bud bank. The vegetative tiller can produce more buds than the reproductive tiller on Hordeum brevisubulatum population, and the age structure of bud from either vegetative tiller or reproductive tiller is an increasing model. An increasing age structure of tiller or bud in the population indicates that the young tillers or buds have taken the predominate status, thereout the population is kept in the "young" period. It is a propagating mechanism to maintain population "forever" existing.Leymus chinensis clonal population expanding with time includes the seasonal changing dynamic of the clone size, the density and height of tiller. The quantity of tiller in clone are expanding with the increasing of clone size when there are enough resource and space in habitat, they are significantly positively correlated to each other. The average length of spacer varies by Hemarthria japonica> Calamagrostis epigeios > Leymus chinensis> C. rigidula > Hierochloe glabra > Arundinella hirta among 6 species of rhizome grass, and is very changeable for each species. Theclone locates daughter tillers by regulating the spacer at length, and the population of rhizo...
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