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Elevated Ozone Concentrations Negatively Impact Forest Growth

Reference
Matyssek, R., Wieser, G., Ceulemans, R., Rennenberg, H., Pretzsch, H., Haberer, K., Low, M., Nunn, A.J., Werner, H., Wipfler, P., Osswald, W., Nikolova, P., Hanke, D.E., Kraigher, H., Tausz, M., Bahnweg, G., Kitao, M., Dieler, J., Sandermann, H., Herbinger, K., Grebenc, T., Blumenrother, M., Deckmyn, G., Grams, T.E.E., Heerdt, C., Leuchner, M., Fabian, P. and Haberle, K.-H. 2010. Enhanced ozone strongly reduces carbon sink strength of adult beech (Fagus sylvatica) -- Resume from the free-air fumigation study at Kranzberg Forest. Environmental Pollution 158: 2527-2532.
The 28 authors of this study, hailing from seven different countries, write that "ground-level ozone (O3), if occurring at concentrations above the pre-industrial range, is potentially the most detrimental of all air pollutants for vegetation (Reich and Amundson, 1985; Bytnerowicz et al., 2003), including trees and forests (Matyssek and Sandermann, 2003)."

In what Matyssek et al. describe as "a unique 8-year free-air O3-fumigation experiment" that was conducted on adult beech (Fagus sylvatica) trees at Kranzberg Forest (Germany), five 60-year-old trees some 28 meters tall had 150 teflon tubes vertically suspended, at 0.5-m distances across their closed foliated canopy, through which O3 was released through pressure-calibrated capillary outlets at 0.3-m intervals at rates that resulted in a doubling of the ambient air's O3 concentration (2 xO3), while an equal number of untreated trees served as ambient (1xO3) controls.

Based upon their experimental analysis, it was determined, in the words of the international research team, that "at stand level, the decline in stem productivity attributable to O3 was 10 m3/ha/year, on average, during the 8-year study period, representing a 44% loss relative to the 1xO3 trees."

Clearly, ozone well deserves to be called one of "the most detrimental of all air pollutants for vegetation, including trees and forests," as Matyssek et al. have written, and as they have found for themselves to be the case for beech trees. So what happens when one adds to a doubling of the atmosphere's debilitating ozone content a less-than-doubling of the air's CO2 concentration, which the U.S. Environmental "Protection" Agency (EPA) has recently labeled a dangerous air pollutant?

In earlier work that was also conducted with beech trees, Liu et al. (2005) found that "elevated CO2 overruled the effects of elevated O3 on non-structural carbohydrates," while Grams et al. (1999) found that "long-term acclimation to elevated CO2 supply counteracts the O3-induced decline of photosynthetic light and dark reactions," and Liu et al. (2004) found that all "adverse effects of ozone on carbohydrate concentrations and contents were counteracted when trees were grown in elevated CO2 [italics added]." And all of this is really good news -- when considered together with a host of other such findings archived under Interactive Effects of CO2 with Ozone on Plant Growth in our Topical Archive.

Additional References
Bytnerowicz, A., Arbaugh, M.J. and Alonso, R. 2003. Ozone air pollution in the Sierrra Nevada: distribution and effects on forests. In: Drupa, S.V. (Ed.), Developments in Environmental Science, Volume 2. Elsevier, p. 402.

Grams, T.E.E, Anegg, S., Haberle, K.-H., Langebartels, C. and Matyssek, R. 1999. Interactions of chronic exposure to elevated CO2 and O3 levels in the photosynthetic light and dark reactions of European beech (Fagus sylvatica). New Phytologist 144: 95-107.

Liu, X.-P., Grams, T.E.E., Matyssek, R. and Rennenberg, H. 2005. Effects of elevated pCO2 and/or pO3 on C-, N-, and S-metabolites in the leaves of juvenile beech and spruce differ between trees grown in monoculture and mixed culture. Plant Physiology and Biochemistry 43: 147-154.

Liu, X., Kozovits, A.R., Grams, T.E.E., Blaschke, H., Rennenberg, H. and Matyssek, R. 2004. Competition modifies effects of ozone/carbon dioxide concentrations on carbohydrate and biomass accumulation in juvenile Norway spruce and European beech. Tree Physiology 24: 1045-1055.

Matyssek, R. and Sandermann Jr., H. 2003. Impact of ozone on trees: an ecophysiological perspective. In: Progress in Botany, Volume 64. Springer-Verlag, Heidelberg, Germany, pp. 349-404.

Reich, P.B. and Amundson, R.G. 1985. Ambient levels of ozone reduce net photosynthesis in tree and crop species. Science 230: 566-570.

Archived 14 December 2010