Tropospheric Ozone Distribution and Injury on Leaves of Sensitive Woody Plants in Nanchang City, China

In recent years, the increase in ozone precursors caused by photochemical reactions has increased plant stress from tropospheric ozone. Ozone pollution is considered the primary cause of forest degradation and tree dieback in Eastern and Western Europe and the United States. Based on urban to exurban investigation in Nanchang city, representing subtropical urban areas in China, and tropospheric ozone concentration monitoring data of Nanchang from April to August 2014, the temporal and spatial distribution characteristics and the effects of tropospheric ozone on plants were studied via ozone injury assessment. The ozone concentration of suburban regions was significantly higher than that of the urban and exurban regions. The highest average concentration of ozone occurred in June, with the AOT40 value reaching 35.5 mg·m^-3·h, well over the 19.6 mg·m^-3·h threshold considered to exert negative influences on the growth of wild plants. Sixteen plant species exhibited typical injury symptoms caused by ozone pollution in suburban and exurban regions, and included exsiccation of the leaf margin, colored spots, patches, and strip coloring between the veins of the upper leaf surface. Furthermore, Cerasus yedoensis (Mats.) Yü et Li, Phoebe sheareri (Hemsl.) Gamble, P. bournei, and Litsea cubeba)(Lour.) Pers. might work as bio-indicators of ozone pollution in Nanchang.