Validation of ozone response functions for annual Mediterranean pasture species using close-to-field-conditions experiments
- 692 Downloads
Ozone (O3) critical levels have been established under the Long-Range Transboundary Air Pollution Convention to assess the risk of O3 effects in European vegetation. A recent review study has led to the development of O3 critical levels for annual Mediterranean pasture species using plants growing in well-watered pots at a coastal site and under low levels of competition. However, uncertainties remain in the extrapolation of the O3 sensitivity of these species under natural conditions. The response of two O3-sensitive annual Mediterranean pasture Trifolium species at the coastal site was compared with the response of the same species growing at a continental site, in natural soil and subject to water-stress and inter-specific competition, representing more closely their natural habitat. The slopes of exposure- and dose-response relationships derived for the two sites showed differences in the response to O3 between sites attributed to differences in environmental growing conditions, growing medium and the level of inter-specific competition, but the effect of the individual factors could not be assessed separately. Dose-based O3 indices partially explained differences due to environmental growing conditions between sites. The slopes showed that plants were more sensitive to O3 at the continental site, but homogeneity of slopes tests revealed that results from both experimental sites may be combined. Although more experimental data considering complex inter-specific competition situations and the effect of important interactive factors such as nitrogen would be needed, these results confirm the validity of applying the current flux-based O3 critical level under close to natural growing conditions. The AOT40-based O3 critical level derived at the coastal site was also considered a suitable risk indicator in close to natural growing conditions in the absence of soil moisture limitations on plant growth.
KeywordsAOT40 Phytotoxic ozone dose Ozone critical levels Stomatal conductance Inter-specific competition Trifolium
The experiments at the continental site were located at Finca Experimental Agrícola La Higueruela (MNCN-CSIC). This study was funded by projects AGRISOST (P2013/ABI-2717), Consejería de Educación, Cultura y Deporte, Comunidad de Madrid (Spain), and by the Spanish Ministry of Agriculture, Fisheries, Food and Environment (MAPAMA).
- CLRTAP (2017) Manual in methodologies and criteria for modelling and mapping critical loads and levels and air pollution effects, risks and trends. Chapter 3, Mapping critical levels for vegetation. Convention on long-range transboundary air pollution. Available at: http://icpmapping.org/Latest_update_Mapping_Manual
- Di Gregorio A, Jansen LJM (2000) Land cover classification system (LCCS): classification concepts and user manual. Food and Agriculture Organization, Rome ISBN 92-5-104216-0. Available at: http://www.fao.org/docrep/003/x0596e/X0596e00.htm#P-1_0 Google Scholar
- Sanz J, Calvete-Sogo H, González-Fernández I et al (2013) Foliar senescence is the most sensitive response to ozone in Bromus hordeaceus and is modulated by nitrogen input. Grass Forage Sci:1–14. doi: 10.1111/gfs.12090
- Thwaites RH (1997) The effects of tropospheric ozone on calcareous grassland communities. PhD Thesis, University of London.Google Scholar