The Research Of Experimental Population Dynamics On Leymus Chinensis And Agropyron Michnoi In The Songnen Plains

Leymus chinensis and Agropyron michnoi are typical clonal plants of perennial herbaceous rhizome of Gramineae.They are salt-tolerant , distributed widely and have higher nutritive value and better palatability to feed animals. In Songnen Plain, the perennial herbages can not only form a single dominant species community, but also accupy the position of subdominant species or companion species.In order to reveal the covergent adaptation of clonal plants vegetative propagation and the growth rhythm , to provide scientific basis for the in-depth study on clonal plants ecology, this paper comparatively analyzes the age structure in the two perennial herbage populations which have grown for three years with different densities and proportions, and also quantitatively analyzes the clonal growth of Agropyron michnoi in the first year of transplanting and Leymus chinensis in the second year that both under cultivated conditions.The results show that there are three age classes in both tillers and rhizome populations of Leymus chinensis and Agropyron michnoi with different densities and proportions. After the growth of the growing season, the tillers of the most plots in two experimental populations had a growing age struture, but rhizome had a stable age structure.In potential populations(winterness seedlings,tiller node shoots and rhizome buds), winterness seedlins of Leymus chinensis and Agropyron michnoi with different densities and proportions consisted of three age classes. Leymus chinensis populations of most plots presented stable age structure,while populations of Agropyron michoni present growing age strucrue. Tiller node of Leymus chinensis and Agropyron michnoi with different densities and proportions also consisted of three age classes,most plots presented growing age strcture; rhizome buds consisted of four age classes, most plots presented stable age structure.Tiller biomass had a stable age structure in the plot that the initial density was 36 plant per square metre with the scale of 1:5 , 1:3 and 3:1 as well as 16 plant per spuare metre with the scale of 1:5, but others had a growing age structure in Leymus chinensis population. However, tiller biomass had a stable age stuctrue in the plot that the initial density was 36 plant per spuare metre with the scale of 1:5,5:1 and 0:1,but others had a growing age structure in Agropyron michnoi population. Rhizome biomass per unit plot had a growing age structure for the most area of Leymus chinensis population, but a stable age structure for the most area of Agropyron michnoi population.Following a season of growth, the large differences on expansion capability had a large phenotypic plasticity in the different clones of Agropyron michnoi.The number of winterness seedlings increased in the form of power function with the increasing of expension plot. However, rhizome length and the number of tillers,tillering node shoots,rhizome shoots and total potential population increased linearly with the expansion of expension area.Following two seasons of growth, there were relasionships with power function among the quantities of components which including tillers, rhizomes and shoots.The number and biomass of tillers, the number of shoots increased linearly with the increasing of floor area in Leymus chinensis clones. Accumulative rhizome length and rhizome biomass increased in the form of power function.