Effects of soil warming during spring on photosynthetic recovery in boreal Norway spruce stands

abonos air temperature amidon calentamiento del suelo chauffage du sol chlorophylle chlorophylls clorofilas engrais fertilizers fluorescence fluorescencia fotosistemas nutrientes nutrients photosynthese photosynthesis photosystem ii photosystems picea abies soil chemicophysical properties soil heating soil temperature stand characteristics starch stems substance nutritive tallo temperatura del aire temperatura del suelo thawing tige