Study on Transpiration Water Consumption and Photosynthetic Characteristics of Landscape Tree Species under Ozone Stress

Abstract

Using Pinus bungeana, Platycladus orientalis, Koelreuteria paniculata and Ginkgo biloba as research objects, three open-top chambers with different ozone-concentration gradients were set up (NF, NF40 and NF80) based on trunk sap-flow technology to study the difference in ozone absorption by trees under different ozone concentrations. The results showed that the monthly and diurnal variations of sap-flow density of different tree species decreased with the increase in ozone concentration, and the increase in ozone concentration reduced the water consumption, ozone uptake rate (FO3), net photosynthetic rate (Pn) and water-use efficiency (WUE) of different tree species. The sap-flow density, water consumption, FO3 and WUE of Koelreuteria paniculata and Ginkgo biloba were higher than those of Pinus bungeana and Platycladus orientalis under different ozone concentrations. The sap-flow density, water consumption, FO3 and WUE of Koelreuteria paniculata and Ginkgo biloba decreased significantly at the ozone concentrations of NF40 and NF80; compared with the ozone concentration of NF, the sap flow density of Koelreuteria paniculata and Ginkgo biloba decreased by 1.04 and 1.03 times as much as that of Pinus bungeana and Platycladus orientalis, respectively; the water consumption of Koelreuteria paniculata and Ginkgo biloba decreased by 1.82 and 1.56 times that of Pinus bungeana and Platycladus orientalis, respectively; the decline rate of FO3 in Koelreuteria paniculata and Ginkgo biloba was 1.30 and 1.04 times that of Pinus bungeana and Platycladus orientalis, respectively; and the decline rate of WUE of Koelreuteria paniculata and Ginkgo biloba was 1.52 and 1.64 times that of Pinus bungeana and Platycladus orientalis, respectively. Pinus bungeana and Platycladus orientalis have stronger tolerance to ozone, while Koelreuteria paniculata and Ginkgo biloba were weak. A variety of conifers can be planted in areas with serious ozone pollution.