| Author |
Adriaenssens, Sandy Wuytack, Tatiana Samson, Roeland Wuyts, Karen Staelens, Jeroen Van Wittenberghe, Shari Boeckx, Pascal Verheyen, Kris |
| Description |
Author Affiliation: Wuyts K ( Laboratory of Environmental and Urban Ecology, Research Group ENdEMIC, Dept. Bioscience Engineering, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium); Adriaenssens S ( Belgian Interregional Environment Agency (IRCEL-CELINE), Kunstlaan 10-11, B-1210 Brussels, Belgium. Electronic address: adriaenssens@irceline.be.); Staelens J ( Flemish Environment Agency (VMM), Kronenburgstraat 45, B-2000 Antwerp, Belgium. Electronic address: jeroen_staelens@yahoo.com.); Wuytack T ( Laboratory of Environmental and Urban Ecology, Research Group ENdEMIC, Dept. Bioscience Engineering, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium. Electronic address: tatiana.wuytack@uantwerpen.be.); Van Wittenberghe S ( Laboratory of Environmental and Urban Ecology, Research Group ENdEMIC, Dept. Bioscience Engineering, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium. Electronic address: shari.vanwittenberghe@uantwerpen.be.); Boeckx P ( Isotope Bioscience Laboratory (ISOFYS), Dept. Applied Analytical and Physical Chemistry, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium. Electronic address: pascal.boeckx@ugent.be.); Samson R ( Laboratory of Environmental and Urban Ecology, Research Group ENdEMIC, Dept. Bioscience Engineering, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium. Electronic address: roeland.samson@uantwerpen.be.); Verheyen K ( Forest & Nature Lab (ForNaLab), Dept. Forest and Water Management, Ghent University, Geraardsbergsesteenweg 267, B-9090 Gontrode-Melle, Belgium. Electronic address: kris.verheyen@ugent.be.) |
| Abstract |
We investigated the influence of leaf traits, rainwater chemistry, and pedospheric nitrogen (N) fertilisation on the aqueous uptake of inorganic N by physiologically active tree leaves. Leaves of juvenile silver birch and European beech trees, supplied with NH4NO3 to the soil at rates from 0 to 200 kg N ha(-1)y(-1), were individually exposed to 100 µl of artificial rainwater containing (15)NH4(+) or (15)NO3(-) at two concentration levels for one hour. In the next vegetative period, the experiment was repeated with NH4(+) at the highest concentration only. The N form and the N concentration in the applied rainwater and, to a lesser extent, the pedospheric N treatment and the leaf traits affected the aqueous foliar N uptake. The foliar uptake of NH4(+) by birch increased when leaves were more wettable. High leaf N concentration and leaf mass per area enhanced the foliar N uptake, and NO3(-) uptake in particular, by birch. Variation in the foliar N uptake by the beech trees could not be explained by the leaf traits considered. In the first experiment, N fertilisation stimulated the foliar N uptake in both species, which was on average 1.42-1.78 times higher at the highest soil N dose than at the zero dose. However, data variability was high and the effect was not appreciable in the second experiment. Our data suggest that next to rainwater chemistry (N form and concentration) also forest N status could play a role in the partitioning of N entering the ecosystem through the soil and the canopy. Models of canopy uptake of aqueous N at the leaf level should take account of leaf traits such as wettability and N concentration. |
