VALORACIÓN DE LA CONTAMINACIÓN ATMOSFÉRICA DEL ÁREA URBANA DE MADRID MEDIANTE BIOINDI- CADORES (LIQUENES EPIFITOS)

The epiphytic lichens ot the urban area of Madrid (about 115 km2) ha ve been studied. 40 stations «ere selected where air pollution would be the only variable ecological factor. In 95 % oi the cases, the selected forophytes were Robinia pseudoacacia and Populus sp- pl. In eacli station forophytes in streets and sidewalks or peripherical ones in parks and squares were recorded. Records show only floristic composition of epiphytic lichen vegetation growing on vertical trunks at a heigth range between 1 and 2 m. In each of the 40 stations the LE BLAKC & DE SLOOVER'S (1970) atmospheric purity inde:; (I A P) was applied. where I A P = S, 1 Q. f/10. With the obtained results, the area studied was mapped in 5 bands so that each band corresponds to a interval of the (1 A Pl. It has been noticed a clear gradient of increased atmospheric purity index between the more polluted area (Arganzuela. \'illaverde) and the north outskirts.