Variation in air pollution tolerance index of plants near a steel factory: Implications for landscape-plant species selection for industrial areas

-Air pollution tolerance index (APTI) is used by landscapers to select plant species tolerant to air pollution. Four physiological and biochemical parameters including leaf relative water content (RWC), ascorbic acid (AA) content, total leaf chlorophyll (TCh), and leaf extract pH were used to develop an APTI. Twenty-three plant species growing near a Beijing steel factory, an air pollution point source, were collected during five dates from July 1 to October 16, 2001. Our data suggested that combining a variety of physiological parameters could give a more reliable result than those air pollution tolerance classifications based on a single biochemical parameter. Through the growing season, some species exhibited APTI variation related to changes in air temperature and water status of the plant. The results highlighted the need for APTI measurements to be conducted throughout the growing season, when evaluating pollution tolerance of individual species. Plant species tolerant or moderately tolerant to air pollution under a variety of environmental conditions include non-trees (shrub, herb, vine) such as Metaplexis japonica, Ampelopsis aconitifolia var. glabra, Rhamnus parvifolia, Ziziphus jujuba var. spinosa, Pharbitis purpurea, Vitex negundo, and trees including Broussonetia papyrifera, Robinia pseudoacacia, and Ailanthus altissima. The APTI of species indicated as an ideal candidate for landscape planting in the vicinity of polluting industry.