Periodic measurements of gas-exchange rates and determinations of foliar N and P concentrations were used for evaluating instantaneous water-use efficiency and photosynthetic nutrient-use efficiency in two co-existing dwarf shrubs of different growth form (V. myrtillus, deciduous, and V. vitis-idaea, evergreen) in a subalpine heath in the southern Alps of Italy. Those data were compared with cumulative assessments of water-use efficiency and photosynthetic nutrient-use efficiency obtained by measuring leaf carbon isotope discrimination in leaf tissues and by estimating nutrient resorption from senescing leaves. V. myrtillus presented higher dry-weight based rates of net photosynthesis (A(weight)) compared to V. vitis-idaea. A(weight) was positively correlated with foliar-nutrient status and intercellular-to-ambient gradient in CO2 concentrations. A(weight) was, furthermore, negatively correlated with leaf specific mass. Instantaneous photosynthetic nutrient-use efficiency did not differ between the two species but the percentages of N and P pools resorbed from senescing leaves were somewhat higher in the deciduous species. The evergreen species showed lower P concentrations in senescing leaves which indicated a higher proficiency in resorbing phosphorus compared to the deciduous species. In addition, the evergreen species achieved a higher carbon gain per unit foliar N and P, due to a longer mean residence time of both nutrients. The two species did not differ from each other with respect to both instantaneous and long-term water-use efficiency. This was consistent with the climatic pattern, showing no sign of water deficiency through the growing season. Current-year V. vitis-idaea leaves had a significantly higher δ13C compared to previous-year leaves, possibly mirroring a long term acclimation of evergreen leaves, as far as they age, to the habitat conditions in the understory where evergreen species are usually confined within mixed dwarf-shrub communities.

Water- and nutrient-use efficiency of a deciduous species, Vaccinium myrtillus, and an evergreen species, V. vitis-idaea, in a subalpine dwarf shrub heath in the southern Alps, Italy

GERDOL, Renato;MARCHESINI, Roberta;BRAGAZZA, Luca
2000

Abstract

Periodic measurements of gas-exchange rates and determinations of foliar N and P concentrations were used for evaluating instantaneous water-use efficiency and photosynthetic nutrient-use efficiency in two co-existing dwarf shrubs of different growth form (V. myrtillus, deciduous, and V. vitis-idaea, evergreen) in a subalpine heath in the southern Alps of Italy. Those data were compared with cumulative assessments of water-use efficiency and photosynthetic nutrient-use efficiency obtained by measuring leaf carbon isotope discrimination in leaf tissues and by estimating nutrient resorption from senescing leaves. V. myrtillus presented higher dry-weight based rates of net photosynthesis (A(weight)) compared to V. vitis-idaea. A(weight) was positively correlated with foliar-nutrient status and intercellular-to-ambient gradient in CO2 concentrations. A(weight) was, furthermore, negatively correlated with leaf specific mass. Instantaneous photosynthetic nutrient-use efficiency did not differ between the two species but the percentages of N and P pools resorbed from senescing leaves were somewhat higher in the deciduous species. The evergreen species showed lower P concentrations in senescing leaves which indicated a higher proficiency in resorbing phosphorus compared to the deciduous species. In addition, the evergreen species achieved a higher carbon gain per unit foliar N and P, due to a longer mean residence time of both nutrients. The two species did not differ from each other with respect to both instantaneous and long-term water-use efficiency. This was consistent with the climatic pattern, showing no sign of water deficiency through the growing season. Current-year V. vitis-idaea leaves had a significantly higher δ13C compared to previous-year leaves, possibly mirroring a long term acclimation of evergreen leaves, as far as they age, to the habitat conditions in the understory where evergreen species are usually confined within mixed dwarf-shrub communities.
2000
Gerdol, Renato; Iacumin, P.; Marchesini, Roberta; Bragazza, Luca
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11392/1203572
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