[Pleurococcus vulgaris, Hypogymna physodes and number of needle year classes on young Norway spruce in Sweden, Denmark, northern Germany and the Netherlands]

alemania algae allemagne azote carga contaminante charge polluante chute des feuilles danemark denmark dinamarca germany indicator plants leaf fall lichen lichenes nitrogen picea abies plantas indicadoras plante indicatrice pollutant load suecia sweden