Concentration of Aerosol Constituents Above and Beneath a Beech and a Spruce Forest Canopy

Abstract

Concentrations of atmospheric aerosol constituents were measured above and beneath the canopies of a beech- and a spruce forest in order to determine the filtering effect of a closed stand of trees. Aerosol concentrations beneath the canopies were significantly lower than those above. In the beech forest, this difference was more pronounced during the leafy period than during the leafless time. The filtering efficiency showed a strong dependence on the size of the aerosol particles with a minimum for particles in the medium size range of about 0.5 μm. radius. The results are compared with dry deposition rates obtained by chemical analyses of precipitation collected above and beneath the tree canopies.