Air Pollution and Vegetation: UNECE ICP Vegetation, Annual Report

Introduction; The UNECE ICP Vegetation2 was established in the late 1980s to consider the science for quantifying damage to plants by ozone and other pollutants. It is one of seven ICPs and Task Forces that report to the Working Group on Effects of the LRTAP Convention on the effects of atmospheric pollutants on different components of the environment (e.g. forests, fresh waters, buildings) and health. With the inclusion of the mosses project within the ICP Vegetation, the programme has expanded to involve over 150 scientists representing 28 Parties to the LRTAP Convention. Over the last year, the remit of the ICP Vegetation has also expanded to include additional studies on heavy metals, flux modelling for vegetation and the impacts of nitrogen pollutants on seminatural vegetation. The ICP Vegetation is led by the UK and has its Coordination Centre at the Centre for Ecology and Hydrology Bangor. The objectives of the ICP Vegetation are designed to meet the requirements of the LRTAP Convention, particularly, at present, the need to provide information for the review of the Gothenburg Protocol to abate acidification, eutrophication and ground-level ozone, planned for 2004/05 (and to be initiated in 2004), and for the possible future development of the Aarhus Protocol on heavy metals. Biomonitoring of pollutant effects on vegetation; The ICP Vegetation collates information on the effects of ambient ozone episodes on crops in Europe and the USA by conducting biomonitoring experiments, and by assessing information in the scientific literature. Ozone episodes can cause short-term responses in plants such as the development of visible injury (small flecks on the upper surface of leaves) or reductions in photosynthesis. If episodes are frequent, longer-term responses such as reductions in growth and yield can occur. Since 1996, participants in the ICP Vegetation have detected effects of ambient ozone at sites across Europe and in the USA by growing ozone-sensitive (NC-S) and ozone-resistant (NC-R) biotypes of white clover (Trifolium repens cv Regal), and recording the occurrence of injury and biomass differences between the two biotypes. In 2001, the mean daily maximum ozone concentration ranged from 34.6 ppb in Sweden to 71.6 ppb in Italy, with the three-month AOT403 ranging from 0.8 ppm.h. to 16.7 ppm.h at the same sites. Visible ozone injury occurred at all of the sites in Europe involved in this survey. For example, in the week starting 9th July, 2001, ozone injury was detected at sites as far apart as Sweden and Italy, as well as a sites in central Europe, such as in Germany. Significant reductions in the biomass of the sensitive biotypes relative to that of the resistant biotypes were found at sites in southern Europe. Data from the 2001 experiments were within the range recorded in previous years. A pilot study using various species of semi-natural vegetation, including ozone-resistant and ozone-sensitive biotypes of Centaurea jacea (brown knapweed) was also conducted in 2001. The results for C. jacea were promising, with ozone injury being detected on the sensitive biotypes at those sites participating.