Ultrastructure in leaves of Fagus silvatica and Carpinus betulus individuals tolerant and susceptible to SO2 and heavy metal pollutants.

The ultrastructure characteristics of leaves during the development of cell organelles, in the "greening process" of spring, have been studied in pollutant-tolerant and susceptible individuals of beech (Fagus silvatica) and hornbeam (Carpinus betulus) in an area polluted with SO2 (the main pollutant may reach 0.06-2.72 mg/m3), heavy metals, and other gases discharged by non-iron metal processing factories. Leaves from tolerant beech and hornbeam individuals did not undergo ultrastructural changes compared to control leaves in an unpolluted area. The susceptible and very susceptible individuals of both species gradually undergo modification in organelle ultrastructure not only during the first steps of greening and momentary exposure to air pollution, but also as a result of long-term exposure to chronic pollution in the forest.