Effect- and Risk-Assessment of Ozone Air Pollution on Forest Vegetation in Switzerland

Rationale

Many studies investigating the negative impacts of ozone on biomass production and physiological functions have demonstrated the relationships between ozone exposure and reductions in both growth and physiological gas exchange leading to an increasing interest in effects of ozone exposure expressed as a critical cumulative exposure of 10’000 ppb hrs above the threshold of 40 ppb (AOT40). Ozone effects on plants, mainly depend on atmospheric transport and stomatal uptake. Thus ozone risk assessments should not only use measured ozone concentrations, but should also account for the influence of atmospheric conditions and soil moisture on stomatal conductance and non-stomatal ozone deposition. Following the Level II approach, this study aims to provide a model to estimate the ozone flux for forest ecosystems throughout Switzerland.

• Abstract, The Swiss Research Information System

Project Aims (2002-2005)

1. Conduct an ozone risk assessment with the development of an ozone deposition model for forest ecosystems based on the existing ODEM (Nussbaum et al., in press) model for crops,
2. The screening and validation of ozone sensitive plant species combined with studies investigating the physiological above- and below-ground plant response under controlled conditions within the validation- and learning center Lattecaldo,
3. The assessment of visible ozone injury in the field, i.e. Level II plots throughout Switzerland and Level I plots in Canton Ticino, applying the UN/ECE ICP-Forests guidelines, and
4. The development of a data bank based web page on visible foliar ozone injury for extension activities.

Although these objectives are investigating different aspects within the proposed research, they are complementary and intended to strengthen the collaboration with our national and international partners, working in the field of ozone effects on vegetation.

Methods

Within the following three years, we intend to continue and foster the collaboration with our international research partners (USA, Spain, Italy, ICP-Forests, UN/ECE) and to use the different ongoing studies within the Lattecaldo OTC research facility, on the long term monitoring Level II plots, as well as on the Level I plots of the Canton Ticino to approach our objectives. In addition to the previous years, we will emphasize the risk assessment of ozone effects on forest plants by developing an ozone deposition model for forest ecosystems based on the existing ODEM for agricultural areas and in close collaboration with the Swiss Federal Research Station for Agroecology and Agriculture FAL, with METEOTEST, and with international collaborators such as Lisa Emberson and Mike Ashmore (University of York). The main challenge will be to combine the different simultaneous studies in a way to take advantage of synergies.

Work plan

The following points have been successfully completed during the 2002 research season:

• Set-up of OTC facility (installation of plastic panels, charcoal filters, and ozone monitoring equipment)
• Assessment of visible ozone injury on a regular basis from beginning of May until end of September
• Measuring of gas exchange during the field season once monthly from May to September with the LiCor 6400 photosynthesis system
• Intensified measurements for physiological parameters from mid July until mid September in combination with fluorescence and morphological measurements in collaboration with F. Bussotti
• Shutting down of OTC facility at beginning of October including harvesting of plant material with C. Hug and P. Bleuler
• Assessment of ozone visible injury in the field from mid August until end of September
• Test applicability of ICP-Forests Sub-Manual on LESS of 16 Level II plots towards end of September (10 field days)
• Assessment of ozone injury on Level I plots within Canton Ticino by field crew
• Passive ozone monitoring from beginning of May until end of September
• Data analysis and publication of results (in process)
• The development of a databank based web page on visible foliar ozone injury and
• The preparation of pictorial data and corresponding comments/text

Work plan for 2003

• Calibration of ODEM with flux data from flux measurements in the field
  studies within Lattecaldo OTC experimental facility
• End of April: set-up of OTC facility with new planting and new plastic panels
• Installation of mesh bags and in-growth cores (spring)
• Intensified site maintenance (watering, weeding)
• Assessment of visible ozone injury on a regular basis from beginning of May until end of September
• Measuring soil respiration and above-ground gas exchange twice monthly in August and September in the PVC rings with or without roots in collaboration with B. Frey
• Assessment of ozone visible injury in the field from mid August until end of September
• Test applicability of ICP-Forests Sub-Manual on LESS and IMP (tree climber) of 16 Level II plots towards end of September
• Assessment of ozone injury on Level I plots within Canton Ticino by field crew
• Passive ozone monitoring from beginning of May until end of September
• Data analysis and publication of results continues

Data

The data from the 2002 research season are currently being analyzed. Preliminary results were presented at the 35th Air Pollution Workshop, Vancouver, BC, Canada. 7-10 April, 2003

Participants and Collaborators

• M. Schaub (WSL), project leader
• N. Kräuchi, (WSL), project leader
• K. Novak (WSL), Ph.D student

• The complete listing of collaborators

Contact

• Marcus Schaub
  

Publications, Posters, Presentations and Extension

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Links

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