Effects of simultaneous ozone exposure and nitrogen loads on carbohydrate concentrations, biomass, growth, and nutrient concentrations of young beech trees (Fagus sylvatica)

Beech seedlings were grown under different nitrogen fertilisation regimes (0, 20, 40 nd 80 kg N ha(-1 yr-1)) for three years and were fumigated and either charcoal-filtered (F) or ambient air (O-3). Nitrogen fertilisation increased leaf necroses, aphid infestations, and nutrient ratios in the leaves (N:P and N:K), as a result of decreased phophorus and potassium concentrations. For plant growth, biomass accumulation, and starch concentrations,whereas soluble carbohydrate concentrations were enhanced. The ozone fumigation resulted in reduced leaf area, leaf water content, shoot growth, root biomass accumulation, and decreased starch, phosphorus, and potassium concentrations, increasing the NY and NX ratios. A combined effect of the two poilutants was detected for the leaf area and the shoot elongation, where ozone fumigation amplified the nitrogen effects. (c) 2005 Elsevier Ltd. All rights reserved.