THE EFFECT OF PESTICIDES ON FOREST SPECIES

Individuals of two woody deciduous species (Carpinus betulus L. and Fa gus sylvatica L.) were grown in a cold tunnel. Plants were treated thr oughout the growth cycle with a mixture of herbicides and insecticides . The lowest dose was equal to average concentrations registered after each rain episode sampled in 2 Italian forests. After approximately 3 5 treatment in a 3-year period stomatal conductance, transpiration, ph otosynthesis and chlorophyll were measured. In Carpinus betulus L. tra nspiration was altered, together with an increase of approximately 40% in the stomatal conductance of individuals reared in the 2 chambers t reated with the higher doses (p<0.05). In Fagus sylvatica L. no effect s on transpiration and stomatal conductance were recorded, while treat ments significantly influenced chlorophyll content (p<0.05), which dim inished by approximately 30%. This difference was also noted between t he control and the chamber treated with the lowest dose. Data on photo synthesis registered differences between the chamber receiving the hig hest dose and the other chambers.