Canopy uptake of N deposition in spruce (Picea abies L. Karst) stands

Abstract

-In order to quantify the total deposition and canopy uptake of N in spruce, plastic Christmas trees were established next to real spruce trees of approximately similar height in clearings of the Strengbach catchment (Vosges mountains, France). Bulk precipitation and throughfall (TF) composition under the artificial trees, the real spruce trees, and in 3 spruce stands aged 15, 35 and 90 years were monitored during 8.5 months. Fluxes of inorganic N, SO 4 2-and Na + in throughfall below plastic trees were 50% (N) to 30% (Na + ) higher to those in bulk precipitation, whereas the flux of water was 30% lower. Net throughfall (NTF) fluxes of NH 4 + were higher below the plastic trees than below the real trees, whereas the reverse was true for NO 3 -. The ratio between total inorganic nitrogen and Na + (or SO 4 2-) in NTF was higher below plastic trees than below closed spruce stands. Assuming that foliar leaching of Na + (or SO 4 2-) was negligible, the ratios between Na + (or SO 4 2-) fluxes in net throughfall under living and plastic canopies were used as deposition indexes, and dry + occult deposition of N was computed for the real spruce trees in the clearings as well as in the 3 closed stands. Results confirmed a significant canopy uptake of dry + occult deposited N and especially NH 4 + by spruce stands. + (pluviolessivat moins pluie) sous les arbres artificiels était supérieur à celui sous les arbres réels, mais inférieur pour le NO 3 -. Le rapport N minéral/ or SO 4 2-(ou Na + ) dans le pluviolessivat net sous les arbres artificiels était supérieur à celui mesuré sous les peuplements fermés. En admettant qu'absorption et lessivage foliaire de Na + et SO 4 2-sont négligeables, nous avons utilisé le rapport entre le pluviolessivat net de Na + (ou or SO 4 2-) sous arbres (ou peuplements) réels et artificiels comme un index de dépôt occulte, et le rapport N minéral/ Na + (ou or SO 4 2-) dans le pluviolessivat net sous les arbres artificiels comme un caractéristique intrinsèque du dépôt occulte. Ceci nous a permis de calculer le dépôt occulte d'azote minéral et l'absorption foliaire dans les différents peuplements étudiés. Les résultats confirment une absorption foliaire d'azote, et plus particulièrement d'NH 4 + , très significative pour la nutrition des peuplements forestiers.dépôt sec / azote / pluviolessivat / secrétion / Picea abiès Ann. For. Sci. 57 (2000) 113-120 113

Relative importance of macrophyte leaves for nitrogen uptake from flood water in tidal salt marshes

“…forest ecosystems (2 to 8%: Boyce et al 1996;up to 5%: Wilson & Tiley 1998). Similarly, as found for aquatic (Touchette & Burkholder 2000) and terrestrial (Wilson 1992, Peuke et al 1998, Ignatova & Dambrine 2000 angiosperms and marine algae (Lotze & Schramm 2000), we found that foliar uptake is generally higher for NH 4 + than for NO 3 -. A linear increase in the uptake rate (Figs.…”

“…Although leaching and the presence of epiphytic macroflora complicates interpretation of throughfall studies (Pearson & Stewardt 1993), it is also evident in terrestrial systems that foliar N-uptake is generally more efficient for NH 4 + than for NO 3 - (Wilson 1992, Peuke et al 1998, Ignatova & Dambrine 2000. In this study, we address the question as to the extent in which foliar uptake of nitrogen contributes to the nutrient demand of halophytic species that grow in the lowest areas of tidal salt marshes.…”

Deposition pattern of precipitation and throughfall in a subtropical evergreen forest in south-central China

“…As indicated by the positive coeffi cient of C x for Ca 2+ and Mg 2+ , the two ions show the signifi cant canopy leaching increased with the concentrations in precipitation during the growing seasons of spring and summer ( Ignatovaa and étienne (2000) found that the canopy uptake of nitrogen deposition was higher in young, fastgrowing stands that had a high N requirement compared with the old and poorly growing stands. Christ et al (1995) and Brumme et al (1999) reported that the increasing NH 4 + concentration in precipitation was accompanied by the increasing retention of NH 4 + , which was similar to our present study.…”

Growth and fructification of a Norway spruce (Picea abies L. Karst) forest ecosystem under changed nutrient and water input

“…It could be shown that high atmospheric nitrogen input has a depressive effect on tree vitality during dry periods [7]. Furthermore, a Norway spruce canopy can uptake especially NH 4 + nitrogen directly from the atmosphere [12]. This makes it more difficult for a balanced nutrient composition of the tree.…”