Abstract: The changing patterns of the quantitative characteristics of mature leaves stomata of Ginko biloba treated with elevat CO₂ and O₃ concontration in open tap chamber (OTC) were Ohsered during 2005 and 2006 growing seasons. The results showed that under 700 μmol CO₂·mol^-1, the stomatal length, width, perimeter, and area were bigger than those of control group (P<0.05); while under 80 μmol O₃·mol^-1, they were smaller than those of control group (P<0.01). nder elevated CO₂, the stomatal density increased slightly (P>0.05), and there was a significant negative correlation between the stomatal index and elevated CO₂ concentration (P<0.05). The elevation of O₃ concentration did not have significant effect on stomatal density (P>0.05), but did on stomatal index. In other words, there was a negative correlation between the stomatal index and the elevation of O₃ concentration. Stomatal specific density was negatively correlated with stomatal length and width, and the correlations could be well expressed with unary quadratic curve equation.

Key words: Ditch wetland, Emerged plants, Nitrogen and phosphorus, Non-point source pollutants