Abstract: In this paper,the concentrations of air negative ions above urban area,suburb green space,and farmland in Nanning city were measured.The results indicated that from the viewpoint of air negative ions,the air quality was in order of large scale suburb green space > farmland > urban area.Vegetation with multi-structure was the best,followed by vegetation with simple structure,and single vegetation pattern.Creek and waterfall could raise the concentration of air negative ions effectively.The concentrations of air negative ions increased with ascending altitude and canopy density,and fluctuated with season.

Key words: Grazing and clipping intensity, Artemisia frigida, Growth, Resource allocation