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This study was conducted to compare the physiological and biochemical responses of four Betulaspecies in response to ozone, and to find out the relationship between ozone uptake rate andphotosynthesis or antioxidant activity. One-year-old seedlings of four Betula sp, B. costata, B. davurica,B. platyphylla var. japonica, and B. ermani, exposed to 100 ppb ozone concentration for 8h day-1 for 5weeks in fumigation chamber. Ozone uptake rate, photosynthesis, SOD and GR activity weremeasured in the leaves of four species once a wek. Cumulative ozone uptake rate was largest in theleaves of B. costata(53.8 mol m-2), smallest in the leaves of B. davurica(35.5 mol m-2). Photosynthesisof four Betula sp. exposed to ozone reduced relative to control, but the photosynthetic responses withchanging stomatal conductance were different among species. Ozone exposure increased SODactivities of four species at the early exposing period, but after a critical point SOD activity decreasedgradually. GR activity of B. costata was similar to the change of SOD activity, but the others showedthe different patterns from B. costata. In conclusion, decreasing both SOD and GR activity at thecritical point, B. costata may be sensitive species in response to ozone. In contrast, the others may beresistant species, which gradually increase GR activity following ozone exposure. GR activity was notalways in accord with the change of SOD activity against ozone uptake, and the different responsesbetwen species were supposed to be affected by the cumulative ozone uptake.