Situation in epicuticular waxes of birch (Betula pendula) leaves in air-polluted regions

The work is aimed at die study of changes in structure and quantity of epic uticular waxes of birch (Betula pendula) leaves in the air-polluted region of die Krusne hory Mts (Ore Mts, Erzgebirge). Samples were taken in the cou rse of three years, regularly twice during the vegetation period on two loc alities of the air-polluted region and on regions without air pollution. On the air-polluted areas the destruction of epicuticular waxes increases wit h increasing altitudes of forest stands. This phenomenon is accompanied by a shrinkage of epicuticular waxes on leaves, In the last two years there wa s a considerable decrease in air pollution load on the whole territory of t he Ore Mts, which resulted in a lesser destruction of epicuticular waxes an d in an increase of the total amount of those waxes on leaves. This favoura ble change manifested itself at the most with stands in higher attitudes. I n spite of the environmental recovery in the Czech Republic, die air pollut ion in die region of the Ore Mts is still higher than it would correspond t o the good growth conditions for birch. The stands are continually being we akened by die immission stress together with action of the unfavourable cli mate. The epicuticular waxes can serve as a bioindicator of die immission l oad.