Growth, photosynthesis and ozone uptake of young beech ( Fagus sylvatica L.) in response to different ozone exposures

Abstract

Beech seedlings (Fagus sylvatica L.) were exposed to episodes of O 3 in environmentally controlled growth chambers during one growing season. Three treatments were applied: charcoal-filtered air, charcoalfiltered air with the addition of 40 ppb O 3 for seven episodes of 5 days' duration (9000-1700 hours), and charcoal-filtered air with the addition of 100 ppb O 3 for seven episodes of 5 days' duration (9000-1700 hours). The accumulated exposure over a threshold of 40 ppb in the last treatment reached 13,911 ppb h. Throughout the growing season we measured growth as well as photosynthetic properties and related effects to external and calculated internal doses of O 3 , using stomatal conductance (g s ) data. Growth, measured as diameter increment and biomass, was not significantly affected by the O 3 treatments. In the 100-ppb treatment, light-saturated CO 2 assimilation rates and chlorophyll content were significantly reduced, and the chlorophyll fluorescence parameter F v /F m was significantly reduced at times of high uptake rates and coincided with strong reductions of assimilation rates. O 3 uptake was lowered in the 100-ppb treatment due to reduced g s . There was serious visible damage by the end of the exposure period in the 100-ppb treatment, while the treatment with 40 ppb O 3 did not seem to cause any significant changes.

Competition increasingly dominates the responsiveness of juvenile beech and spruce to elevated CO2 and/or O3 concentrations throughout two subsequent growing seasons

“…While in 1999, aboveground growth parameters of beech were hardly affected by O 3 , 1 year later, O 3 effects were obvious, in particular, when comparing mono‐ and mixed cultures (again confirming hypothesis 3). Likewise, Bortier et al . (2001, 2000) did not find O 3 ‐induced changes in shoot biomass in beech seedlings within one growing season.…”

Foliar physiology of yellow-poplar ( Liriodendron tulipifera L.) exposed to O 3 and elevated CO 2 over five seasons.

“…This suggests a shift in the allocation of surplus carbon below ground. N nutrition can be an important mediator of the impacts of elevated CO 2 and O 3 (Bortier and Vandermeiren 2001). When N is limiting, trees can be less responsive to elevated CO 2 .…”

Early Responses to Acute Ozone Exposure in Two Fagus Sylvatica Clones Differing in Xeromorphic Adaptations: Photosynthetic and Stomatal Processes, Membrane and Epicuticular Characteristics

“…Ozone exposure may induce a transient increase in stomatal conductance in F. sylvatica (Leonardi, Langebartels, & Sandermann, 1990), a persistent decrease in photosynthetic performance (Bortier, Ceulemanns, & De Temmerman, 2000;Dixon, Le Thiec, & Garrec, 1998;Grams, Anegg, Häberle, Langebartels, & Matyssek, 1999;Lippert et al, 1996;Paludan-Müller, Saxe, & Leverenz, 1999), a premature leaf fall (Mikkelsen & Heide-Jørgensen, 1996), visible foliar injuries (Bortier, Vandermeiren, De Temmerman, & Ceulemans, 2001;Vollenweider, Ottiger, & Gün-thardt-Goerg, 2003), and reduced (Braun & Flückiger, 1995;Krause & Höckel, 1995;Mortensen, BastrupBirk, & Ro-Pulsen, 1995;Paludan-Müller et al, 1999;Pearson & Mansfield, 1994) or unchanged (Bortier et al, 2001) growth rates.…”