Observation and confirmation of foliar ozone symptoms of native plant species of Switzerland and southern Spain

Tropospheric ozone is considered as the major pollutant of concern to the health and productivity of forests in the eastern United States and has more recently become of increasing concern within the forests of southern Europe. Recent observations have dearly demonstrated foliar injury symptoms to be occurring on many tree and native plant species within remote forested areas. Several plant genera (and a few species within genera) found in both the forests of Switzerland and the southern coastal region of Spain exhibit field symptoms typical of ambient ozone exposures. Ozone exposures for many species have been conducted under controlled CSTR conditions and within open- top chambers within the study areas. Results have confirmed that the O₃-like foliar symptoms as observed under natural forest and open grown conditions for many native tree, shrub, and herbaceous species in Spain and Switzerland are caused by exposures to ambient O₃.