Environmental Pollution 169 (2012) 249
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Ozone, climate change and forests
Ground-level ozone (O3) is the air pollutant with the highest damage potential for forests, and is also recognized as a signiﬁcant greenhouse gas (Paoletti, 2007). Background levels in the Northern Hemisphere have increased around 2–4.5 times since the pre-industrial age (Vingarzan, 2004). Recent control measures were not successful (EEA, 2011). Climate change is expected to further enhance O3 production (The Royal Society, 2008). Although many questions remain, we now know a great deal about how O3 affects forests at the cell/leaf level (by inducing a cascade of biochemical, physiological and morphological responses) and at the tree/canopy level (by affecting allocation and carbon strength, reproduction, hydrology and the response to co-occurring stressors) (Paoletti, 2007). Forest ecosystems, however, are very complex. There is a need to scale from the cell and leaf level up to the ecosystem and regional level, to integrate ozone and climate change effects, and to develop a biologically signiﬁcant and usable standard to protect forests from O3 in such a changing environment (Paoletti and Manning, 2007). A method for assessing the risk of damage to vegetation has been developed that involves modeling the ﬂux of O3 into the plant (Emberson et al., 2000) and has the potential to incorporate the effects of climate on stomata. A consensus about how to parameterize the plant ability of detoxifying O3 has not been reached yet, although efforts are available (e.g. Paoletti et al., 2008; Di Baccio et al., 2008). Knowledge gaps still exist and should be ﬁlled by applying novel techniques of ozone exposure in free air, because exposure under controlled conditions, e.g. closed or open-top chambers, has often resulted into misleading results and an overestimation of O3 impacts (Paoletti, 2007). The conference “Ozone, climate change and forests” was organised by the COST Action FP0903 ‘Climate change and forest mitigation and adaptation in a polluted environment’, and was attended by 90 participants from 25 countries. Ozone ﬂuxes and effects, monitoring of O3 effects, O3 standards for forests, interaction of O3 effects with climate change, and O3 effects on the belowground part of forest ecosystems (in collaboration with the COST FP0803 ‘Belowground carbon turnover in European forests’) were the subjects of most interest. Insights from crop science were given by ICP Vegetation. Three papers from the conference are published in this issue of Environmental Pollution. One paper is about openair fumigation (Díaz de Quijano et al., in this issue) and two papers
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are about ﬂuxes (Fares et al., in this issue; Zapletal et al., in this issue). Further papers from the conference will be published in Journal of Environmental Monitoring, and one is already available in iForest (H unová and Schreiberová, in press). References Di Baccio, D., Castagna, A., Paoletti, E., Sebastiani, L., Ranieri, A., 2008. Could the differences in O3 sensitivity between two poplar clones be related to a difference in antioxidant defense and secondary metabolic response to O3 inﬂux? Tree Physiology 28, 1761–1772. Díaz de Quijano, M., Penuelas, J., Menard, T., Vollenweider, P. Ozone visible symptoms and reduced root biomass in the subalpine species Pinus uncinata after two-years of free-air ozone fumigation. Environmental Pollution, in this issue. EEA (European Environment Agency), Nov 09, 2011. Air Quality in Europe – 2011 Report. Denmark, Copenhagen. Emberson, L.D., Wieser, G., Ashmore, M.R., 2000. Modelling of stomatal conductance and ozone ﬂux of Norway spruce: comparison with ﬁeld data. Environmental Pollution 109, 393–402. Fares, S., Park, J.-H., Weber, R., Gentner, D., Karlik, J., Goldstein, A.H. Ozone deposition to an orange orchard: partitioning between stomatal and non-stomatal sinks. Environmental Pollution, in this issue. H unová, I., Schreiberová, M. Ambient ozone phytotoxic potential over the Czech forests as assessed by AOT40. iForest – Biogeosciences and Forestry, in press. Paoletti, E., Manning, W.J., 2007. Toward a biologically signiﬁcant and usable standard for ozone that will also protect plants. Environmental Pollution 150, 85–95. Paoletti, E., Ranieri, A., Lauteri, M., 2008. Moving toward effective ozone ﬂux assessment. Environmental Pollution 156, 16–19. Paoletti, E., 2007. Ozone impacts on forests. CAB reviews: perspectives in agriculture, veterinary science. Nutrition and Natural Resources 2 (68), 13. The Royal Society, 2008. Ground-level Ozone in the 21st Century: Future Trends, Impacts and Policy Implications. Report 15/8. The Royal Society, London, 132 pp. Vingarzan, R., 2004. A review of surface O3 background levels and trends. Atmospheric Environment 38, 3431–3442. Zapletal, M., Pretel, J., Chroust, P., Cudlín, P., Edwards-Jonásová, M., Urban, O., Pokorný, R.M., Czerný, R., H unová, I. The inﬂuence of climate change on stomatal ozone ﬂux to a mountain Norway spruce forest. Environmental Pollution, in this issue.
Elena Paoletti* IPP-CNR, Via Madonna del Piano 10, 50019 Sesto Fiorentino, Italy Pavel Cudlin Global Change Research Centre CAS, Na Sadkach 7, 370 05 Ceske Budejovice, Czech Republic * Corresponding author. E-mail address: [email protected]