Effects of environmental stress on forest crown condition in Europe. Part III: estimation of critical deposition and concentration levels and their exceedances

acid deposition air pollution aluminio aluminium azote base saturation boreal forests dioxyde de soufre environmental factors environmental impact escandinavia europa europa occidental europe europe occidentale facteur du milieu factores ambientales forest decline forest health impact sur l'environnement impacto ambiental marchitez del bosque monitoring nitrogen ozone ozono pollution du sol sanidad de los bosques saturation scandinavia scandinavie soil pollution sotobosque sulphur dioxide undergrowth vigilancia western europe