The changes of the vegetation characteristics of alfalfa grasslands under different fertilization schemes were analyzed with the trial of plot experiments.The results indicate that the species richness index of the continuous cropping alfalfa grassland did not significantly change under different fertilizer treatments

along with considerably increased community coverage

and significantly raised community heights. Fertilization could maintain species diversity and community stability and enhance alfalfa grassland productivity.After the application of fertilizer

the niche breadth of alfalfa population significantly increased and the competitiveness strengthened relatively.However

the niche breadth of forbs decreased and relatively weakened.No significant niche overlap was found between alfalfa population and other species under continuous cultivation and fertilization.Greater niche overlap was found among the forbs

between which the competition was more intense and dominant.Fertilization could improve the quality and economic value of alfalfa grasslands

while the invasion of forbs functional groups such asSetaria viridiswas one of the most important factors degrading the grasslands.