Effects of environmental stress on forest crown condition in Europe. Part I: hypotheses and approach to the study

air pollution climatic factors defoliation drought environmental factors environmental impact escandinavia espagne europa europa meridional europe europe du sud facteur climatique facteur du milieu factores ambientales fagus sylvatica forest decline forest health geographical distribution impact sur l'environnement impacto ambiental marchitez del bosque meteorological elements monitoring picea abies pinus sylvestris quercus ilex quercus petraea quercus robur sanidad de los bosques scandinavia scandinavie site factors southern europe spain stand characteristics temperatura temperature vigilancia