松嫩平原碱化草甸天然虎尾草种群密度制约特征的研究

STUDY ON SPECIFICITIES OF THE DENSITY DEPENDENCE TO NATURAL CHLORIS VIRGATA POPULATION OF ALKALIZATION MEADOW IN THE SONGNEN PLAIN OF CHINA

Chloris virgata is an annual tuft grass which is more alkali tolerance. According to the investigation and the analysis of natural Ch. virgata population of alkalization meadow in the Songnen plain of China, the best correlations among simulated functions were selected to be the specifiitics of intraspecific competition and density dependence of the population in this paper. The results showed that there were the power function y = ax-b between mean tuft weight and the tuft density;the power function y = ax-b in joint-booting stage, and the exponential funfiaon y = ae-bx in ripening stage, between mean plantweight and the density; the linear function y = a-bx between tillering rate and the density; the exponential functiony = ae-bx between earing rate, ear weight per unit area, mean weight per ear, mean number of spike per ear, mean numler of spikelet per ear, or above-ground biomass, and the density of the population. Through comparisons of the parameters to corresponding specificities in both growth periods of joint-booting stage and ripening stage, the results showed that due to intraspecific competition, all the quantitative specificities of the population had their effects of density dependence increased along with growth and development of Ch.virgata.