Schaub, M., Kaennel Dobbertin, M., & Steiner, D. (Eds.). (2008). Air pollution and climate change at contrasting altitude and latitude. 23rd IUFRO conference for specialists in air pollution and climate change effects on forest ecosystems. Murten, Switze

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P ollution and Climate Change Effects on F orest Ecosystems. Abstracts

Air Pollution and Climate

Change at Contrasting Altitude and Latitude

23

^rd

IUFRO Conference for Specialists in Air Pollution and Climate Change Effects on Forest Ecosystems

Murten, Switzerland September 7–12, 2008

Abstracts

iufro_proceedings_us.qxp:Layout 1 15.8.2008 10:26 Uhr Seite 1

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Air Pollution and Climate

Change at Contrasting Altitude and Latitude

23

^rd

IUFRO Conference for Specialists in Air Pollution and Climate Change Effects on Forest Ecosystems

Murten, Switzerland September 7-12, 2008 Abstracts

Edited by

Marcus Schaub, Michèle Kaennel Dobbertin and Doris Steiner

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Organizing Committee Marcus Schaub

Swiss Federal Research Institute WSL, Birmensdorf, Switzerland Christian Hug

Swiss Federal Research Institute WSL, Birmensdorf, Switzerland Peter Bleuler

Swiss Federal Research Institute WSL, Birmensdorf, Switzerland Susanne Raschle

Swiss Federal Research Institute WSL, Birmensdorf, Switzerland Michèle Kaennel Dobbertin

Swiss Federal Research Institute WSL, Birmensdorf, Switzerland Doris Steiner

Swiss Federal Research Institute WSL, Birmensdorf, Switzerland

Scientific Board Rainer Matyssek

Technical University of Munich TUM, Freising, Germany Marcus Schaub

Swiss Federal Research Institute WSL, Birmensdorf, Switzerland Gerhard Wieser

Research and Training Centre for Forests, Natural Hazards and Landscape BFW, Innsbruck, Austria

Elena Paoletti

Institute of Plant Protection, National Council of Research, Florence, Italy

Recommended form of citation

Schaub, M., Kaennel Dobbertin, M., Steiner, D. (Eds) 2008. Air Pollution and Climate Change at Contrasting Altitude and Latitude. 23rd IUFRO Conference for Specialists in Air Pollution and Climate Change Effects on Forest Ecosystems. Murten, Switzerland, 7-12 Sept 2008. Abstracts. Birmensdorf, Swiss Federal Research Institute WSL. 162 pp.

Electronic version available from Library WSL

Zürcherstrasse 111 CH-8903 Birmensdorf

Url: http://www.wsl.ch/publikationen/books/index_EN

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Foreword

The focus of the conference is on impacts and interactions of air pollutants and climate change on the tree performance across latitudinal and altitudinal ranges. In particular, the regional specificities of tree and ecosystem responsiveness to anthropogenic stressors such as elevated CO2 and O3 regimes, enhanced nitrogen deposition and scenarios of climate change, as represented through altered seasonal temperature and moisture regimes will be emphasized. The overall aim of the conference is the advancement in risk assessment: which are the consequences for carbon sink strength in respect to the post-Kyoto policies? How are strategies such as the critical levels concept in risk assessment to be defined and evaluated by exposure versus dose-related approaches of stress

diagnosis? How realistic are potentials towards process-based, i.e. mechanistic concepts for risk assessment? In respect to the above questions the state of the art will be highlighted.

We cordially invite you to this conference and would be delighted to address the air pollution and climate change effects on forests which will provide a broad, cause-effect related basis for environmental policy making.

Marcus Schaub, WSL Rainer Matyssek, TUM Gerhard Wieser, BFW Elena Paoletti, IPP-CNR

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While changes in the long-term mean state of climate will have many important consequences on numerous environmental, social, and economic sectors, the most significant impacts of climatic change are likely to arise from shifts in the intensity and frequency of extreme weather events. Indeed, insurance costs resulting from extreme weather events have been steadily increasing over the last two decades, in response to both population pressures in regions that are at risk, but also because of the frequency and severity of certain forms of extremes are changing. Regions which have been safe from catastrophic wind storms, heat waves, and floods are increasingly becoming more vulnerable to these events. The associated damage costs would consequently be extremely high.

Some attention will be given to the impacts that changes in mean climate and also extreme events may have on forests, and the feedbacks of forest structures on climate, both in the tropical countries and the mid-latitude zones. It will be seen that many of the processes involved are a complex mix of social, environmental and technological factors. A holistic view is thus necessary to address climate/forest issues and in order to respond to the needs of the

“end-user community” (i.e., policy makers and the general public) with a view of finding adequate, sustainable solutions to these problems.

Chair for Climate Research, University of Geneva, Switzerland

Elements of climatic change and extremes relevant to forests

Opening keynote

Corresponding author: Martin Beniston (Martin.Beniston@unige.ch)

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Rainer Matyssek (1), David Karnosky (2), Gerhard Wieser (3)

Contrasting with the 1980s, when the anthropogenic enhancement of tropospheric ozone (O3) was controversially debated as a factor driving local forest decline phenomena, this agent has gained global importance, given the well-proven long-distance transport across continents and predicted new "hot spots" of O3 emission in many parts of the world. Although immediate O3 risk of dying trees and forests is presently regarded to be unlikely, consensus exists about the high injurious potential of enhanced O3 regimes and their chronic risks that, can result from interaction with other factors such as elevated CO2, parasites, drought). In view of "climate change" scenarios, O3-induced long-term mitigation of the carbon sink strength of tree

vegetation has become a new concern, also with respect to post-Kyoto policies. Hence, reliable cause-effect based O3 risk assessment of trees and forests has become more important than ever. Still, knowledge about O3 effects on trees is dominated by the outcome of experimental studies with juvenile individuals under growth conditions of limited ecological significance.

Available information of this kind mostly shows distinct O3 sensitivity, although evidence is inconsistent across tree species and genotypes as well as successional status (pioneer vs.

climax) or growth habit (evergreenness vs. deciduousness). New perspectives towards

ecologically meaningful clarification have been opened, through advances in free-air fumigation methodology, allowing controlled experimentation with enhanced O3 regimes, also in

combination with elevated CO2, on mature trees in plantations and forests. Two prominent studies of this latter kind were Aspen FACE (Rhinelander, USA) and CASIROZ/SFB 607 (Freising, Germany), key findings of which will be cross-compared and examined for consistencies.

Tendencies emerge of ameliorating effects of elevated CO2 on O3 impact, or inversely, of the potential of O3 in mitigating C sink strength under high CO2 supply. Evidently, tree

responsiveness is largely biased through the kind of competition and interactions with parasites and drought. Pioneer tree species appear to be more sensitive to O3 than climax species, becoming evident within Aspen FACE (Populus tremuloides/Betula papyrifera vs. Acer

saccharum) compared to CASIROZ/SFB 607 (Fagus sylvatica vs. Picea abies). Comparisons will be extended towards experimental findings on O3 responsiveness from the harsh timberline ecotone of the European Alps, exemplifying Larix decidua (deciduous pioneer) vs. Pinus cembra (evergreen climax species). In demonstrating such comparisons, the need for basing O3 risk assessment on mechanistic grounds will become evident, the latter being defined through the biophysics of O3 uptake (i.e., actual O3 dose) and the metabolic sensitivity expressed on an O3 uptake basis (i.e., effective dose). Novel experimental concepts for

achieving this task will be addressed, enabling for tree-stand process scaling and new modeling tools for O3 risk assessment. On the grounds of methodological advances and recent evidence (1) Ecophysiology of Plants, Technische Universität München, Freising, Germany

(2) School of Forest Resources and Environmental Science, Michigan Technological University, Houghton, MI, USA

(3) Dept. Alpine Timberline Ecophysiology, Federal Office and Research Centre for Forests, Innsbruck, Austria

Advances in understanding ozone risk in forest trees: key messages from Aspen FACE and CASIROZ/SFB 607

Session 1: Mechanisms of action and indicator development

Corresponding author: Rainer Matyssek (matyssek@wzw.tum.de)

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Filippo Bussotti (1), Chiara Cascio (1), Reto J. Strasser (2), Marcus Schaub (3), Giacomo A.

Gerosa (4)

This paper re-analyzes fluorescence data from open-top chamber (OTC) experiments, already published by different research groups, in order to individuate some general features of ozone stress on woody plants.

The experiments were carried out by Swiss and Italian research groups at the experimental research facilities of the Lattecaldo cantonal forest nursery (Switzerland, managed by the Swiss Federal Research Institute WSL, Birmensdorf) and the Curno regional forest nursery (Italy, managed by FLA, Milan and Catholic University at Brescia). The experimental settings were similar and consisted of four charcoal filtered (CF) and four non-filtered air chambers (NF, where O3 concentrations are about 92% in respect to ambient air). The woody species

assessed were: Fraxinus excelsior, Prunus avium, Viburnum lantana, Fagus sylvatica, Populus nigra and Quercus robur. Ozone levels (AOT40 April-September) were close to 25 ppm·h at both sites, for all the considered years.

Chl a fluorescence transients of intact leaves were measured by means of direct fluorescence at different times during the seasons. On a logarithmic time scale, the rising transient from F₀ (when all the reaction centres of the PSII are open, i.e. when the primary acceptor quinone Q_A is fully oxidised) to FP (where FP = FM under saturating excitation light) had a polyphasic behavior. The analysis of the transient is called the JIP-test.

Ambient ozone concentrations lead to the closure of reaction centres (RC), which function as dissipater centers. All the parameters connected to dissipation were also increased. The quantum yield efficiency (FV/FM) demonstrated only little sensitivity. The response was not proportional to ozone exposition and/or fluxes. During the first part of the season, leaves were very resilient and photosynthesis could be transiently stimulated by ozone. Only towards the end of the growing season, efficiency and performance parameters showed a sudden drop. For species with terminated growth during the first part of the season, ozone has little effect on carbon fixation and storage. Growth was significantly reduced in species with a continuous growth pattern. The comparison of the shape of FT normalized per F₀ and F_M and per F₀ and F_J shows evident peaks at the steps K, J and I. Each peak corresponds to specific biochemical events. K indicates the reduced efficiency in the water splitting system. J indicates a QA

accumulation in the single turnover region. I-peak seems to be more specifically connected to ozone stress due to the inactivation of Rubisco.

(1) University of Florence, Dept. of Plant Biology, Firenze, Italy

(2) University of Geneva, Bioenergetics Laboratory, Jussy-Geneva, Switzerland (3) Swiss Federal Research Institute WSL, Birmensdorf, Switzerland

(4) Dipartimento di Matematica e Fisica, Università Cattolica del Sacro Cuore, Brescia, Italy

General features of ozone stress on woody plants, detected by the chlorophyll a fluorescence transient (FT)

Corresponding author: Filippo Bussotti (filippo.bussotti@unifi.it)

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Mireille Cabané (1), Brigitte Pollet (2), Jean-Claude Pireaux (1), Nicolas Richet (1), Françoise Huber (3), Jacques Banvoy (1), Patrick Perré (3), Pierre Dizengremel (1), Catherine Lapierre (2)

The industrial development has led to an increase in the concentration of atmospheric carbon dioxide but also resulted in an increase of tropospheric ozone concentrations. Ozone has been suggested to cause the greatest amount of damage to vegetation as compared to other gaseous pollutants. Plants submitted to various biotic or abiotic stresses respond with a stimulation of the phenylpropanoid pathway, especially in the case of oxidative stress induced by wounding and pathogen attack. This activation was associated to an increase in lignin synthesis near the site of infection (or wounding), which supports a role of lignin in disease resistance in leaves.

In a similar way, we showed that ozone induced an increase of the phenylpropanoid pathway suggesting a possible role of lignin in ozone resistance. Various plant species were cultivated in phytotronic chambers with different levels of ozone. In all cases, we showed a coordinated increase of several enzymes involved in phenolic synthesis and particularly in lignin synthesis in response to ozone treatment in leaves. The stimulation of enzyme activities was generally associated with a higher Klason lignin content in extract-free leaves. In addition, stress lignins synthesized in response to ozone displayed a distinct structure, relative to constitutive lignins.

The highest changes in lignification and in enzyme activities were obtained with the highest ozone dose. All these results suggested a possible role of lignin in tolerance to ozone by limiting the necrosis extension.

Ozone combined with elevated carbon dioxide resulted in similar observations. Nevertheless, the stimulation of lignin biosynthesis was less marked than with ozone alone. High carbon dioxide could lower the detrimental effect of ozone in leaves.

In stems, ozone reduced lignin biosynthesis probably due to lower availability in carbon skeletons. The modifications in cell-wall component synthesis were related to anatomical modifications and some wood properties.

(1) UMR1137 INRA-Nancy Université, Ecologie et Ecophysiologie Forestières, Nancy, France (2) UMR 206 AgroParisTech-INRA, AgroParisTech, Centre de Grignon, France

(3) LERMAB, ENGREF, Nancy, France

Effects of ozone and elevated carbon dioxide on lignification in leaves and stems

Corresponding author: Mireille Cabané (cabane@scbiol.uhp-nancy.fr)

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Carlo Calfapietra, Silvano Fares, Francesco Loreto

Volatile Organic Compounds (VOCs) emitted from vegetation (particularly isoprenoids) represent an important source of the atmospheric hydrocarbons (Guenther et al., 1991).

Biogenic VOC emissions almost double the anthropogenic source. When biogenic VOCs mix with NOx in the presence of UV radiation, ozone is being formed. Biogenic contribution to ozone formation is particularly frequent around conurbations, or following wind transport over areas with anthropic pollution. This topic is particularly important in Mediterranean regions, since optimal conditions for ozone formation in terms of VOC/NOx ratios, abundance of UV radiation, and presence of urban areas and recurrent wind regimes, are present for long periods of the year. Moreover, Mediterranean vegetation includes several species that are strong and evergreen isoprenoid emitters, and high temperatures for part of the year further stimulate these temperature-dependent emissions.

Emission of isoprenoids can be an evolutive mechanism to cope with ozone from the plant standpoint. Isoprenoids have been reported to remove and detoxify ozone in plants (Loreto et al., 2004). We present here current knowledge on the impact of rising ozone levels on

isoprenoid emission (Calfapietra et al., 2007), and evidences showing that species that emit isoprenoids are more protected against oxidative stress because of isoprenoid antioxidant functions (Loreto and Fares, 2007). This trait not only influences plant tolerance to ozone but also may substantially alter the flux of ozone between atmosphere and biosphere.

References:

Calfapietra, C., Wiberley, A.E., Falbel, T.G., Linskey, A.R., Scarascia Mugnozza, G., Karnosky, D.F., Loreto, F., Sharkey, T.D., 2007. Isoprene synthase expression and protein levels are reduced under elevated O3 but not under elevated CO2 (FACE) in field-grown aspen trees.

Plant, Cell and Environment 30, 654-661.

Guenther, A.B., Monson, R.K., Fall, R., 1991. Isoprene and monoterpene emission rate variability: Observations with eucalyptus and emission rate algorithm development, Journal of Geophysical Research 96, 799-808.

Loreto, F., Pinelli, P., Manes, F., Kollist, H., 2004. Impact of ozone on monoterpene emission and evidence for an isoprene-like antioxidant action of monoterpens emitted by Quercus ilex leaves. Tree Physiology 24, 361–367.

Loreto, F., Fares, S., 2007. Is ozone flux inside leaves only a damage indicator? Clues from volatile isoprenoid studies. Plant Physiology 143, 1096-1100.

National Research Council (CNR)-Institute of Agro-Environmental & Forest Biology (IBAF), Monterotondo Scalo (Roma), Italy

Volatile organic compounds from vegetation and their interaction with ozone

Corresponding author: Carlo Calfapietra (carlo.calfapietra@ibaf.cnr.it)

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Pierre Dizengremel (1), Yves Jolivet (1), Didier le Thiec (2), Marie-Paule Hasenfratz-Sauder (1), Matthieu Bagard (1)

Long-term exposures of higher plants to low ozone concentrations affect biochemical processes prior to any detectable symptoms of visible injury. On the other hand, the current critical level of ozone used to determine the threshold for damaging plants (biomass loss) is still based on the seasonal sum of the external concentrations of the pollutant above 40 nL.L^-1 (AOT40). A more relevant concept developed a flux-based approach taking into account the actual ozone flux in the leaf through the stomata (cumulative uptake of ozone=CUO). CUO however ignores the internal capacity of leaf defense, which led to the concept of "effective ozone flux", a balance between stomatal flux and the intensity of cellular detoxification (Musselman et al., 2006; Paoletti and Manning, 2007; Wieser and Matyssek, 2007).

Although the direct detoxification of ozone (and ROS) can primarily be carried out by cell wall ascorbate, the existing level of ascorbate is not sufficient as a good indicator for the degree of cell sensitivity (D’Haese et al., 2005). A regeneration of the antioxidant barrier is needed, implying an increased production of reducing power (NAD(P)H). It is made possible through the increased participation of the catabolic pathways. In addition, the large change in the rubisco/PEPcase ratio, due to a huge increase in activity of the latter enzyme, leads to changes in carbon isotopic discrimination which could, in turn, modify water use efficiency. The

challenge is to adjust these indicators in a leaf-model system (Dizengremel et al., 2008).

References:

D’Haese, D., Vandermeiren, K., Asard, H., Horemans, N., 2005. Other factors than apoplastic ascorbate contribute to the differential ozone tolerance of two clones of Trifolium repens L.

Plant, Cell and Environment 28, 623-632.

Dizengremel, P., Le Thiec, D., Bagard, M., Jolivet, Y., 2008. Ozone risk assessment for plants:

central role of metabolism-dependent changes in reducing power. Environmental Pollution, in press.

Musselman, R.C., Lefohn, A.S., Massman, W.J., Heath, R.L., 2006. A critical review and analysis of the use of exposure- and flux-based ozone indices for predicting vegetation effects.

Atmospheric Environment 40, 1869-1888.

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.

Wieser, G., Matyssek, R., 2007. Linking ozone uptake and defense towards a mechanistic risk assessment for forest trees. New Phytologist 174, 7-9.

(1) University Henri Poincaré Nancy 1, Vandoeuvre, France (2) INRA Nancy, Champenoux, France

Reducing power dependent on metabolic changes as an indicator of effective ozone phytotoxicity

Corresponding author: Pierre Dizengremel (pierre.dizengremel@scbiol.uhp-nancy.fr)

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Matthias Dobbertin, Britta Eilmann, Peter Bleuler, Arnaud Giuggiola, Elisabeth Graf Pannatier, Werner Landolt, Andreas Rigling

Climate change scenarios predict increasing temperature and reduced precipitation during summer in central and southern Europe. In the Rhone valley of Switzerland Scots pine (Pinus sylvestris) forests are already declining with high mortality rates following dry and hot

summers. Mean annual precipitation for pine forests ranges from 500 to 900 mm, in drought years as low as 300 mm.

An irrigation experiment was set up in 2003 in a 90 year old Scots pine forest, located at 600 m altitude with annual precipitation of 600 mm. The four irrigated and four control plots were randomly assigned. They are 0.1 ha in size with 75 trees on average. The irrigation, which is carried out at night during the monthsof April to October, roughly doubled the mean annual precipitation. Various tree crown parameters were annually assessed on all trees, including relative foliage amount in 5%-steps and mortality. In 2004, 13 dominant trees were selected, 7 from the irrigated and 6 from the control plots covering the whole range of foliage classes.

Their inter-annual growth was assessed weekly using the pinning method. These trees were harvested in April 2006 and analyzed for tree ring width, stable carbon isotope ratios, shoot and needle length, fresh and dry weight and projected needle area.

Irrigation had a significant effect on all of the parameters. But tree foliage class also correlated significantly with most parameters showing the influence of the sample tree selection. Mean needle length, fresh and dry needle weight, shoot length and ring width all correlated positively with estimated foliage amount. Specific leaf area and dry/fresh needle weight were negatively correlated. Water use efficiency, as estimated from stable carbon isotope ratios, correlated highly with a calculated drought index and was higher for trees with lower foliage amount.

Trees with more foliage began stem growth earlier and ended later than trees with low foliage.

Irrigation increased foliage amount between 2003 and 2007 by roughly 6%, while trees in control plots showed a loss of 10% foliage, probably due to the dry years 2003-2005. Mortality was 6.1% on the control plots as compared to 2.5% on the irrigated plots. Irrigation increased needle length by up to 70%, shoot length up to 100%, ring width up to 150% of the control trees. Ring width and water use efficiency reacted already in the first year of irrigation, shoot and needle length with a one-year delay. Irrigated trees showed longer stem growth and a delayed earlywood/latewood transition than control trees. Their water-use efficiency decreased significantly, even for trees for lower foliage amount.

Swiss Federal Research Institute WSL, Birmensdorf, Switzerland

Response of mature Scots pines to drought stress: comparing various foliar and stem wood indicators

Corresponding author: Matthias Dobbertin (dobbertin@wsl.ch)

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Raphael Mainiero (1), Marian Kazda (2)

Rising ozone (O3) levels were shown to reduce carbon-investments into the fine root system of Fagus sylvatica. Studies dealing with the influence of O3 on fine roots, however, did not

consider the pronounced temporal dynamics found in this species (Mainiero and Kazda, 2006).

The present study thus focuses on the influence of elevated O3 concentrations on (i) the temporal patterns of fine root growth and mortality in relation to seasonal changes of soil temperature and water content and (ii) fine root longevity. Using minirhizotrons, stands of mature F. sylvatica were studied in Southern Germany during 2004. Stands under ambient O3 levels (1xO3) were compared to fumigated trees being exposed to doubled O3 concentrations (2xO3, maximum of 150 ppb).

Under the 1xO3 regime, fine root growth and mortality were correlated (p<0.01). Fine root growth scaled positively to soil temperature (p<0.001). Fine root mortality increased with both soil temperature and water content (p<0.01). Thus, fine root turnover accelerated during favorable soil conditions and shed fine roots were replaced immediately by new ones. In contrast, under elevated ozone concentrations, fine root growth and mortality were not correlated. Fine root mortality showed a significant relationship to soil temperature and water content (p<0.001) but fine root growth was not significantly related to soil conditions.

Final survival for non-mycorrhizal roots did not differ significantly between the plots (1xO3:

41%, 2xO3: 33%, study period: 190 d). Differences, however, appeared for median fine root longevity (1xO3: 112 d, 2xO3: 170 d) and hazard functions, i.e. the age specific failure rate, indicating a retardation in non-mycorrhizal fine root shedding as a compensatory response to altered turnover patterns. No differences were found for mycorrhizal fine roots (1xO3: 15%, 2xO3: 19%).

The data suggest rising O3 levels to alter temporal patterns of fine root dynamics in F.

sylvatica rather than its magnitude. Interacting with seasonally changing soil conditions, these altered patterns might lower the root system efficiency.

References:

Mainiero, R., Kazda, M., 2006. Depth-related fine root dynamics of Fagus sylvatica during exceptional drought. Forest Ecology and Management 237, 135-142.

(1) Institute For Applied Plant Biology IAP, Schönenbuch, Switzerland (2) Ulm University, Ulm, Germany

Fine root dynamics of Fagus sylvatica and the influence of elevated ozone concentrations

Corresponding author: Raphael Mainiero (raphael.mainiero@iap.ch)

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Rocío Alonso, Susana Elvira, Victoria Bermejo, Ignacio González-Fernández, Benjamín S.

Gimeno

The high levels of ozone frequently recorded in the Mediterranean region have promoted in the last years the research into ozone sensitivity of species characteristic of the forests of this area. A new approach based on stomatal ozone flux uptake has been adopted in Europe under the Convention of Long-Range Transboundary Air Pollution (UNECE-CLRTAP) framework for establishing ozone critical levels for the protection of vegetation. Considering stomatal ozone uptake instead of atmospheric exposure allows incorporating some modifying factors of plant ozone sensitivity such as species type, phenology and the influence of environmental

conditions.

Previously reported experiments performed in open-top chambers (OTC) have described that ozone affected the metabolism of Pinus halepensis, Quercus ilex and Quercus coccifera seedlings, causing reductions of biomass and/or gas exchange rates, and disturbing plants ability to withstand other environmental stresses. These ozone-induced alterations have been revised to study the relationships between the observed effects and stomatal pollutant uptake.

Ozone fluxes to the different species throughout the experiments were calculated using the EMEP ozone deposition model (DO3SE, Deposition of Ozone and Stomatal Exchange). Specific parameterizations for each species recently published were used for the stomatal conductance model. The suitability of using accumulated ozone flux uptake to predict effects on

Mediterranean evergreen vegetation will be discussed.

Ecotoxicology of Air Pollution, CIEMAT (Ed. 70), Madrid, Spain

Relating ozone effects on Mediterranean evegreen forests species with ozone uptake fluxes: a review of experiments in Spain

Corresponding author: Rocío Alonso (rocio.alonso@ciemat.es)

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Carlos Calderón Guerrero (1,2), Madeleine S. Günthardt-Goerg (1), Pierre Vollenweider (1)

Holm oak (Quercus ilex L.) is a widespread and typical evergreen tree species of the

Mediterranean sclerophyll vegetation with as yet undescribed ozone symptoms. Air pollution in the city of Madrid, Spain is mainly caused by a dense road traffic as seen within large

conurbations (about 5.4 millions inhabitants). Considering Madrid's climate, the detrimental effect of ozone on plants is likely to affect trees in urban parks which provide valuable services for public recreation and air filtration.

Within the framework of a PhD thesis about the impact of air pollution on urban trees of Madrid, abiotic ozone-like symptoms were detected in Q. ilex. In the present study, material was sampled in June and October 2007 from three mature Holm oaks planted on a sunny and irrigated lawn strip near the Atocha train station in Madrid (650 m a.s.l.) to diagnose the cause of visible symptoms. Injury was documented at the site. Branch samples, with up to four leaf generations and sometimes two leaf flushes per year, were collected and stored in a

herbarium. Structural changes in fixed leaf discs were investigated using hand- and semi-thin cuttings. AOT40 indices were calculated on the basis of hourly means of ozone concentration provided by a municipality air monitoring station in the vicinity.

The climate in Madrid is mediterranean and continental but summer drought at the sampling site was alleviated by automatic irrigation. In 2007, AOT40 (April to September) amounted to 7.55 ppm·h vs. 13.45, 9.0, 11.26 and 14.55 ppm·h in 2006 back to 2003, respectively (Total AOT40 2003–2007 = 55.80 ppm·h). Ozone concentrations were thus rather low in Madrid. The main visible injury appeared macroscopically as a bronze shading of the upper leaf surface increasing with leaf age and light exposure and appearing in C+1 and older foliage. Under a magnifying glass, the change in color was caused by dense brownish stipples separated by strands of still greenish tissues thinning out with increasing leaf age; the lower leaf side always remained asymptomatic. Stipples were underlaid by discrete groups of necrotic cells showing typical markers of oxidative stress and hypersensitive responses. The other factors of stress which were detected (dust deposition, insects and fungi) did not cause injuries in the

mesophyll. Despite sclerophilly, ozone symptoms in foliage could be confirmed (which site irrigation probably strengthened). Moreover, similar visible injury was found at 14 other sites throughout the Madrid area. Hence holm oak appeared to be sensitive to even moderate level of ozone exposure.

(1) Swiss Federal Research Institute WSL, Birmensdorf, Switzerland (2) Universidad Politécnica de Madrid, Madrid, Spain

Visible and microscopic ozone symptoms in Quercus ilex

Corresponding author: Carlos Calderón Guerrero (pierre.vollenweider@wsl.ch)

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Izabella Franiel (1), Anna Błocka (2)

Fluctuating asymmetry (FA) is a non-specific stress indicator which describes developmental instability in the bilateral structure of plant organs. The FA factor is mostly used to characterize the level of ecological stress in plants. Moreover, it is widely assumed that the high value of leaf FA in trees is a result of a high level of environmental pollution.

In this work we analyzed the FA response to abiotic stress in Betula pendula Roth leaves on two contrasting sites (air polluted vs. air unpolluted site). We also investigated for which other leaf feature, beside width and surface, the FA factor can be determined as an environmental stress indicator. Having done the discriminant analysis, cluster analysis and mixed-model ANOVA procedure, we selected one feature, which was an apical angle. There was a significant decrease in apical angle FA in birch leaves from the unpolluted site as compared to the polluted one. These results suggest that plants living in stressful conditions are usually more

symmetrical than plants from undisturbed habitats. Furthermore, the leaf FA of plant species with wide ecological distribution such as B. pendula can be used to indicate the quality of environment.

References:

Allenbach, D.M., Sullivan, K.B., Lydy, M.J., 1999. Higher fluctuating asymmetry as a measure of susceptibility to pesticides in fishes. Environmental Toxicology and Chemistry 18, 899-905.

Dimitriou, I., Aronsson, P., Weih, M., 2006. Stress tolerance of five willow clones after irrigation with different amounts of landfill leachate. Bioresource Technology 97, 150-157.

(1) University of Silesia, Katowice, Poland (2) Central Mining Institute, Katowice, Poland

Leaf fluctuating asymmetry of Betula pendula Roth as an indicator of environment quality

Corresponding author: Izabella Franiel (izabella.franiel@us.edu.pl)

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Irina Neta Gostin

The emissions of air pollutants from the various industrial and social activities have a large impact on the vegetal organisms growing in these areas. In this paper, the structural changes from leaves and young stems of Abies alba specimens collected from polluted sites (from the adjacent area of the Ceahlau National Park in Romania) and from the park area were

investigated. The simultaneous effects of heavy metals, dust and nitric oxides (the main pollutants from these area) were studied.

The structure of conducting and mechanic tissues, the leaf shapes and dimensions, the variation in mesophyll thickness, the distribution and the frequency of the stomata were examined. The cuticle morphology which is a very important structure as it is the first barrier for the pollutant agents which enter in the leaf (Bermadinger–Stabentheier, 1995), was investigated by SEM technology. The specimens collected from the polluted environments showed a low frequency of stomata and changes in the epicuticular wax structure. Plants can synthesize and accumulate a comprehensive spectrum of phenolics in response to physiological stimuli and stress (Dixon and Paiva, 1995). Both, in the stem and in the leaf dark phenolic deposits could be observed. Considerable reduction in leaf area was also observed. Tracheid modifications (tangential diameter, tangential lumen diameter, wall thickness) were also investigated.

The results for specimens collected from a less polluted area were quite the opposite.

Subsidiary cell complexes remained the same for all the populations, while the range in the size of the stomata showed little variation. For the factors in the stem, at the polluted sites, the sclerenchyma presented some modifications such as incomplete development of the fibers or fibers with thin or waved walls. Structural and micromorphological changes could serve as pollution markers and to evaluate the impact of the anthropogenic activity on the forest ecosystems.

References:

Dixon, R.A., Paiva, N.L., 1995. Stress-induced phenylopropanoid metabolism. The Plant Cell 7, 1085–1097.

Bermadinger–Stabentheier, E., 1995. Physical injury, re-crystallization of wax tubes and artefacts: identifying some causes of structural alteration to spruce needle wax. New Phytologist 130(1), 67–74.

University Al. I. Cuza Iasi, Romania

Histological, morphological and micromorphological changes in Abies alba leaves and young stems under the influence of air pollutants

Corresponding author: Irina Neta Gostin (irinagostin@yahoo.com)

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Jožica Gričar (1), Primož Oven (2), Tom Levanič (1)

We investigated the wood formation dynamics of Norway spruce (Picea abies) from two different sites in Slovenia: Pokljuka, an Alpine site (1250 m a.s.l.) and Sorsko polje, a lowland plantation (350 m a.s.l). The study was carried out over three years (2002–2004) and

examined the formation of xylem growth-ring pattern in Norway spruce at both sites during the abnormally dry and hot summer of 2003 in comparison to the relatively normal growing seasons of 2002 and 2004.

Microscopical examination of cross-sections revealed that the onset of cell division in the cambium differed with regard to the site and year. Radial growth-ring patterns in Norway spruce grown at both sites, totally differed in 2003 which was abnormally dry and warm, from the relatively normal years 2002 and 2004. Xylem growth rings at the Alpine site (Pokljuka) were wider in 2003, whereas trees in the lowland plantation (Sorsko polje) experienced premature cessation of cambial activity due to the lack of precipitation, resulting in narrower xylem growth rings. Final widths of the xylem growth ring varied among years more at Sorsko polje, suggesting that they are greatly influenced by climatic factors. The most intense cell production of Norway spruce which occurred around the summer solstice (21 June), was shifted towards the beginning of the growing season at Sorsko polje in 2003. Curves of the Gompertz function describing wood formation dynamics were in all cases steeper at Pokljuka, indicating a higher rate of cell production at this site. Comparisons of earlywood portions and final width of the xylem growth rings revealed that the narrower xylem rings of Norway spruce at Pokljuka contained more latewood than the wider rings at Sorsko polje. On the other hand, the period of earlywood formation in narrower xylem rings in 2003 at Sorsko polje was longer than in 2002 and 2004, which could be explained by premature cessation of cambial activity.

Our research confirms previous observations on the effect of climate change on tree growth (e.

g. Jolly et al., 2005). The limiting effect of precipitation on Norway spruce growth generally decreases and the importance of air temperature increases with increasing latitude and altitude. Namely, trees above a certain altitude will temporarily benefit from higher temperatures, whereas the radial growth of trees from lower areas will decrease.

References:

Jolly, W.M., Dobbertin, M., Zimmermann, N.E., Reichstein, M., 2005. Divergent vegetation growth responses to the 2003 heat wave in the Swiss Alps. Geophysical Research Letters 32, L18409, doi:10.1029/2005GL02352.

(1) Slovenian Forestry Institute, Ljubljana, Slovenia

(2) University of Ljubljana, Biotechnical Faculty, Ljubljana, Slovenia

Effect of the warm and dry 2003 growing season on wood formation dynamics in Norway spruce at two elevations in Slovenia

Corresponding author: Jožica Gričar (jozica.gricar@gozdis.si)

Schaub, M., Kaennel Dobbertin, M., & Steiner, D. (Eds.). (2008). Air pollution and climate change at contrasting altitude and latitude. 23rd IUFRO conference for specialists in air pollution and climate change effects on forest ecosystems. Murten, Switze

P ollution and Climate Change Effects on F orest Ecosystems. Abstracts

Air Pollution and Climate

Change at Contrasting Altitude and Latitude

23

IUFRO Conference for Specialists in Air Pollution and Climate Change Effects on Forest Ecosystems

Murten, Switzerland September 7–12, 2008

Abstracts

Air Pollution and Climate

Change at Contrasting Altitude and Latitude

23

IUFRO Conference for Specialists in Air Pollution and Climate Change Effects on Forest Ecosystems

Murten, Switzerland September 7-12, 2008 Abstracts

Edited by

Marcus Schaub, Michèle Kaennel Dobbertin and Doris Steiner

Foreword

Contents

0

Session 1: Mechanisms of action and indicator development

1

Session 2: Atmospheric deposition, soils and nutrient cycles

2

Session 3: Joint session on concept and application of critical loads for forests

3

Session 4: Integrated effects of multiple stressors 4

Session 5: Genetic aspects 5

Session 6: Detection, monitoring and evaluation 6

Session 7: Risk assessment and modeling 7

Elements of climatic change and extremes relevant to forests

Advances in understanding ozone risk in forest trees: key messages from Aspen FACE and CASIROZ/SFB 607

General features of ozone stress on woody plants, detected by the chlorophyll a fluorescence transient (FT)

Effects of ozone and elevated carbon dioxide on lignification in leaves and stems

Volatile organic compounds from vegetation and their interaction with ozone

Reducing power dependent on metabolic changes as an indicator of effective ozone phytotoxicity

Response of mature Scots pines to drought stress: comparing various foliar and stem wood indicators

Fine root dynamics of Fagus sylvatica and the influence of elevated ozone concentrations

Relating ozone effects on Mediterranean evegreen forests species with ozone uptake fluxes: a review of experiments in Spain

Visible and microscopic ozone symptoms in Quercus ilex

Leaf fluctuating asymmetry of Betula pendula Roth as an indicator of environment quality

Histological, morphological and micromorphological changes in Abies alba leaves and young stems under the influence of air pollutants

Effect of the warm and dry 2003 growing season on wood formation dynamics in Norway spruce at two elevations in Slovenia

Session 4: Integrated effects of multiple stressors ⁴

Session 5: Genetic aspects ⁵

Session 6: Detection, monitoring and evaluation ⁶

Session 7: Risk assessment and modeling ⁷