Abstract: Negative air ions (NAIs) in urban green space play an important role in improving habitant health. Urban green area has great difference in its NAIs with the natural forest environment or urban industrial area, and thus, an intuitive, scientific, and accurate model of grading and evaluating ANIs is critical to evaluate the NAIs level in urban green space. In this paper, two models for grading and evaluating NAIs, Anbei evaluation model and forest air evaluation model, were employed to evaluate the NAIs concentration in Beijing Olympic Forest Park. There existed great differences in the ANIs concentration and air clear degree among sampling sites, due to the differences in plant community structure, vegetation type, and vegetation coverage. Through the comparison of the evaluation results of the two models, it was found that forest air ion evaluation index could comprehensively and systematically reflect the differences in the NAIs concentration among different sites, being convenient for public’s understanding, and more applicable to the grading of NAIs concentration and the evaluation of air clear degree of urban green space represented by the Beijing Olympic Forest Park. Opposite to the forest air ion evaluation index, the gradation standard of NAIs concentration had some deficiencies. A partial revision of this standard was made so as to make it more suitable for the analysis and assessment of the NAIs concentration in urban green space.

Key words: Rice, Allelopathic variety, Water, Fertility and light, Allelocehmical, Secondary metabolite