The Dynamics of the Grassland Vegetation : 2 The dispersive structures of the plant individuals in population of several pastures

Abstract

Using Iδ index (Morisita), the dispersive structures of the plant individuals in population of several pastures were examined. The results are summarized as follows: 1. At the beginning of establishment, the dispersive structures of the plant individuals population of pastures became contagious as the results of heterogeneities of seeding and germination. With growth of individuals, the death of slender plants occurred frequently in the places with high plant density. Therefore the dispersive structures changed from the contagious phase to the random by degrees. 2. The changes of dispersive structures were accelerated by hard competition under the high levels of fertilizer application and the few frequencies of cutting. 3. The mode of distribution on composition of species in pastures correlated with the degree of dominance. The dispersive structures of dominant species showed random and those of inferior species showed contagious. Further the examination was conducted to analyze the condition and trend of several pastures based on the dispersive structures.