Einfluß von Mineralstoffernährung, Ozon und saurem Nebel auf Photosynthese-Parameter und stomatäre Leitfähigkeit von Picea abies (L.) Karst

CO₂ response and light response of CO₂ uptake and H₂O release give a quantitative measure for physiological changes due to pollutants and different mineral nutrition. Photosynthetic parameters and stomatal regulation were found to be affected by pollutants depending on the nutritional status. In all plants which were polluted with ozone and which were not fertilized, maximum carboxylation capacity V _m ^c, maximum net photosynthesis rate A_m (at saturating light and saturating CO₂ partial pressure), apparent quantum yield Q.Y., and regulation ability of the stomata were reduced considerably. The light compensation point and the CO₂ compensation point are considerably enhanced. After fertilization with Mg and Ca, increase photosynthetic capacity was observed. The results of this experiment, in particular the analysis of the photosynthetic and stomatal behaviour, support the hypothesis that the forest decline at high altitudes of the Bavarian Forest (Bayerischer Wald) is caused by a combination of ozone pollution and acid deposition from the atmosphere, particularly with magnesium deficiency (Bosch et al. 1983). Injuries by ozone alone, however, are more pronounced than injuries by acid mist alone.