The Study On Competition Of Three Main Dominant Species On Typical Grassland

Competition makes the morphology and life history of natural plant in a process of dynamic change, which leading to the whole community structure changing. Competition is divided into interspecific competition and intraspecific competition, and one of the main reason leading the vegetation succession and community constitute is interspecific competition. Therefore, research and discussion on typical grassland of dominant species competition and development trend of grassland degradation are of great importance. In this paper, use the wild removal test and interior control experiment to research three major advantages grasses in Maodeng ranch in the city of Xilinhot, using the removing method to set Leymus chinensis., Stipa krylovii., Cleistogenes squarrosa. single and mixed samples in the field, and to measure and record its height, tillers, biomass and using the factors controlling test to Leymus chinensis. and Stipa krylovii. in the room. To exploit the response surface method to analyze the mix proportion, moisture content, density in different condition (including height, tiller number and biomass) and energy consumption for competition. The results show that:(1) In the field condition, indicators of single Leymus chinensis. of height, tillers, biomass were less than the mixed, but these indicators were greater than mixed with Stipa krylovii. and Cleistogenes squarrosa..The Cleistogenes squarrosa.were affected by the strongest competition.(2) In low water environmental conditions, the drought resistance power show that Stipa krylovii. stronger than Leymus chinensis., therefore, less water has little effect for Stipa krylovii. growing; high water environmental condition is favorable for Leymus chinensis. and inhibition for Stipa krylovii..(3) In high density environment, intraspecific competition of Leymus chinensis. is stronger when it occupied a large proportion, but the intraspecific competition of Stipa krylovii. is more weak when it possessed a large proportion. In low density environment, two kinds of forage grass could grow well.(4) The final winner is who can earlier occupy a large proportion of plants in the community. The communities can keep species diversity because of the effect of intraspecific and interspecific competition, finally, the stability structure of grassland community has been built.(5)Leymus chinensis. can consume the least energy when Leymus chinensis. and Stipa krylovii. at the same ratio mixed, but Stipa krylovii. can consume the least when they are in the 2:8 proportion mixed. The ability of fixed energy for growth of Leymus chinensis. and Stipa krylovii. were just the opposite in different periods. Leymus chinensis. fixed maximum energy in the heading period and fixed Minimum energy fructicative period, and Stipa krylovii. contrary to it. In the late growth period, the energy consumption increased of both Leymus chinensis. and Stipa krylovii.To explore the competitive relationship between the dominant grass in the typical steppe community, would be helpful to understand the degradation of steppe community, the reason and succession and predict the future development trend of steppe community.The study provides scientific evidence for the protection of prairie ecological balance.