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Conclusions and Outlook

What can be concluded?

  • Even the doubling of ozone concentrations did not weaken beech
    trees substantially over the period of five years.
  • Effects on stem growth were below statistical significance.
  • Nevertheless,
    at cell & leaf level, many O3 responses were detected,
    O3 responses varied between years,
    sun & shade leaves displayed similar O3 sensitivity, and
    O3 effects on roots and mycorrhiza were detected.
  • During the drought of 2003 ozone intake was similar to 2004 in
    spite of much higher concentrations in 2003.
  • Chronic O3 effects cannot be ruled out, although acute short-term
    risks were not substantiated.

What to do?

  • No arguments for changing of critical levels or doses.
    There is no acute risk detectable for beech.
    Beech is not the most sensitive species.
  • Do not take young trees as surrogate of old ones.
  • O3 intake rather than external O3 concentration is relevant when assessing the risk potential.

Flyer download

The CASIROZ project is summarized in a flyer available for download here (pdf file, about 2 MB).


The CASIROZ project published many results in the Plant Biology special Issue "Ozone sensitivity of adult frest trees" Plant Biology 9(2), march 2007, pages 163 - 356:

Matyssek R, Bahnweg G, Ceulemans R, Fabian P, Grill D, Hanke DE, H. Kraigher, Oßwald W, Rennenberg H, Sandermann H, Tausz M, Wieser G (2007) Synopsis of the CASIROZ case study: Carbon Sink Strength of Fagus sylvatica L. in a Changing Environment - Experimental Risk Assessment of Mitigation by Chronic Ozone Impact. Plant Biology 9: 163-180

Karnosky D-F, Werner H, Holopainen T, Percy K, Oksanen T, Oksanen E, Heerdt C, Fabian P, Nagy J, Heilman W, Cox R, Nelson N, Matyssek R (2007) Free-Air Exposure Systems to Scale up Ozone Research to Mature Trees. Plant Biology 9: 181-190

Oksanen E, Kontunen-Soppela S, Riikonen J, Peltonen P, Uddling J, Vapaavuori E (2007) Northern environment predisposes birches to ozone damage. Plant Biology 9: 191-196

Löw M, Häberle K-H, Warren C, Matyssek R (2007) O3 flux-related responsiveness of photosynthesis, respiration and stomatal conductance of adult Fagus sylvatica to experimentally enhanced free-air O3 exposure. Plant Biology 9: 197-206

Blumenröther M, Löw M, Matyssek R, Oßwald W (2007) Flux-based response of sucrose and starch in leaves of adult beech trees (Fagus sylvatica L.) under chronic free-air O3 fumigation. Plant Biology 9: 207-214

Haberer K, Grebenc T, Alexou M, Gessler A, Kraigher H, Rennenberg H (2007) Effects of Long-Term Free-Air Ozone Fumigation on delta15N and Total N in Fagus sylvatica and Associated Mycorrhizal Fungi. Plant Biology 9: 242-252

Alexou M, Hofer N, Liu X, Rennenberg H, Haberer K (2007) Significance of Ozone Exposure for Inter-Annual Differences in Primary Metabolites of Old-Growth Beech (Fagus sylvatica L.) and Norway Spruce (Picea abies L.) Trees in a Mixed Forest Stand. Plant Biology 9: 227-241

Jehnes S, Betz G, Bahnweg G, Haberer K, Sandermann H, Rennenberg H (2007) Tree Internal Signalling and Defence Reactions under Ozone Exposure in Sun and Shade Leaves of European Beech (Fagus sylvatica L.) Trees. Plant Biology 9: 253-264

Winwood J, Pate A-E, Price A-J, Hanke D-E (2007) Effects of long-term, free-air ozone fumigation on the cytokinin content of mature beech trees. Plant Biology 9: 265-278

Grebenc T, Kraigher H (2007) Changes in the community of ectomycorrhizal fungi and increased fine root number under adult beech trees chronically fumigated with double ambient ozone concentration. Plant Biology 9: 279-287

Herbinger K, Then C, Löw M, Haberer K, Alexou M, Remele K, Rennenberg H, Grill D, Matyssek R, Wieser G, Tausz M (2007) Gas exchange and antioxidative compounds in young beech trees under free-air ozone exposure and comparisons to adult trees. Plant Biology 9: 288-297

Zeleznik P, Hrenko M, Then C, Koch N, Grebenc T, Levanic T, Kraigher H (2007) CASIROZ: Root Parameters and Types of Ectomycorrhiza of Young Beech Plants Exposed to Different Ozone and Light Regimes. Plant Biology 9: 298-308

Then C, Herbinger K, Blumenröther M, Haberer K, Heerdt C, Oßwald W, Rennenberg H, Grill D, Tausz M, Wieser G (2007) Evidence that branch cuvettes are reasonable surrogates for estimating O3 effects in entire tree crowns. Plant Biology 9: 309-319

Deckmyn G, Op de Beeck M, Löw M, Then C, Verbeeck H, Wipfler P, Ceulemans R (2007) Modelling Ozone Effects on Adult Beech Trees through Simulation of Defence, Damage, and Repair Costs: Implementation of the CASIROZ Ozone Model in the ANAFORE Forest Model. Plant Biology 9: 320-330

Op de Beeck M, Löw M, Verbeeck H, Deckmyn G (2007) Suitability of a combined stomatal conductance and photosynthesis model for calculation of leaf-level ozone fluxes. Plant Biology 9: 331-341

Kubiske M-E, Quinn V-S, Marquardt P-E, Karnosky D-F (2007) Effects of Elevated Atmospheric CO2 and/or O3 on Intra- and Interspecific Competitive Ability of Aspen. Plant Biology 9: 342-355

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   last change Nov 5, 2007 by Löw • matyssek@wzw.tum.de