Abstract: By using opentop chamber, this paper studied the effects of elevated CO₂(700 μmol·mol^-1) and O₃(100 nmol·mol^-1) concentrations and their combination on the leaf membrane lipid peroxidation and antioxidant system of two years old Oligostachyum lubricum. After 30 days exposure to elevated O₃ concentration, the activity of the leaf antioxidant system and the contents of the leaf osmotic adjusting substances increased, the ability of eliminating reactive oxygen production enhanced, but the malondialdehyde content had less change, suggesting that the O. lubricum could tolerate shortterm O₃ stress. After 90 days exposure to elevated O₃, the activity of leaf antioxidant system decreased while the leaf malondialdehyde content increased significantly, and the cell membrane structure was seriously damaged. After 30 days exposure to elevated CO₂ concentration, both the activity of leaf antioxidant system and the contents of leaf osmotic adjusting substances increased, suggesting that O. lubricum had a definite physiological adaptability to high CO₂ oncentrations. After 90 days exposure to elevated CO₂ concentration, the activity of leaf antioxidant system and the contents of leaf reactive oxygen species decreased significantly, and the leaf soluble sugar and protein contents increased, which benefited the growth of O. lubricum. Under the effects of the combination of elevated CO₂ and O₃, the O. lubricum leaves could maintain high levels of antioxidant activity and osmotic adjustment substances contents to effectively regulate the balance between reactive oxygen species production and clearance, indicating that elevated CO₂ could mitigate the oxidative stress in certain degree.

Key words: urbantorural green space, soil, water soluble organic carbon, temperature sensitivity, available phosphorus.