Assessing the impact of ozone on photosynthesis of European beech (Fergus sylvatica L.) in environmental chambers

Interactions of chronic exposure to elevated CO2 and O3 levels in the photosynthetic light and dark reactions of European beech (Fagus sylvatica)

“…Lippert et al (1996b) observed a similar progression of O $ injury when beech was exposed to similar growth conditions at ambient CO # and four different O $ regimes between 0.2 and 2.0iambient O $ . Also the O $ -induced decline in CE, PC, Φ CO# was confirmed by Lippert et al (1996b) and was consistent with several other studies on F. sylvatica (Mikkelsen, 1995 ;Zeuthen et al, 1997 ;Dixon et al, 1998) and other tree species (Matyssek et al, 1991(Matyssek et al, , 1993Samuelson, 1994 ;Kull et al, 1996 ; 1996a ; Wieser, 1997). The observed decline in the area-based CO # uptake rate was not only due to the spreading of necrotic lesions in the leaf area, but relating CE and PC to the leaf chlorophyll content (cf.…”

“…Expressing the ' critical level for ozone ' according to Ka$ renlampi & Ska$ rby (1996) as an AOT 40 dose (i.e. accumulated O $ exposure above a threshold of 40 nl l −" ), a value of 50 µl l −" h, as found by Lippert et al (1996b) to lower the photosynthetic capacity of F. sylvatica by 10%, had not been reached during the first measurement period (Fig. 1).…”

“…Chronic exposure to enhanced O $ levels is regarded to be injurious, in particular, to broad-leaf trees including F. sylvatica, as a decline in photosynthesis, premature leaf loss and increased dark respiration may limit the biomass production (Matyssek et al, 1991(Matyssek et al, , 1993Pearson & Mansfield, 1993, 1994Mikkelsen, 1995 ;Lippert et al, 1996b ;Mikkelsen & Heide-Jo$ rgensen, 1996 ;Langebartels et al, 1997 ;Zeuthen et al, 1997 ;Ska$ rby et al, 1998). Plant sensitivity to ozone has often been found to relate to the stomatal conductance, as high O $ influx through the stomata may increase the risk of injury (Reich, 1987 ;Barnes & Wellburn, 1998 ;Volin et al, 1998).…”

Effects of ozone exposure on growth and photosynthesis of beech seedlings (Fagus sylvatica)

“…As for other tree species, the following common effects of ozone stress have been reported for beech : acceleration of leaf senescence (Mikkelsen & HeideJorgensen, 1996), visible damage, reduced photosynthetic performance (Pearson & Mansfield, 1993 ;Lippert et al, 1996 ;Dixon et al, 1998), and reduced growth rates (Pearson & Mansfield, 1994 ;Braun & Flu$ ckiger, 1995 ;Krause & Ho$ ckel, 1995 ;Mortensen et al, 1995).…”

“…The latter found better correlations of biomass data with the 24 h dose than with daylight dose, and suggested that ozone during night time is also important. Lippert et al (1996) correlated photosynthesis data for beech with AOT40 values and concluded that these were inadequate indicators for their results. It is possible that the critical level for photosynthesis should be lower than for biomass (Ska$ rby & Karlsson, 1996), and the question arises whether a limit of 40 ppb is appropriate for processes other than growth.…”