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Nitrogen nutrition and isotope differences among life forms at the northern treeline of Alaska (1994)

Schulze, E.-D. ; Chapin, F. S. ; Gebauer, G.

Springer

Oecologia 100 (1994), S. 406-412

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ISSN: 1432-1939

Keywords: Boreal forest ; Nitrogen, phosphorus, and cation nutrition ; Stable isotopes ; Picea glauca Calamagrostis Vaccinium

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Natural abundances of nitrogen isotopes, δ15N, indicate that, in the same habitat, Alaskan Picea glauca and P. mariana use a different soil nitrogen compartment from the evergreen shrub Vaccinium vitis-idaea or the deciduous grass Calamagrostis canadensis. The very low δ15N values (-7.7 ‰) suggest that (1) Picea mainly uses inorganic nitrogen (probably mainly ammonium) or organic N in fresh litter, (2) Vaccinium (-4.3 ‰) with its ericoid mycorrhizae uses more stable organic matter, and (3) Calamagrostis (+0.9 ‰) exploits deeper soil horizons with higher δ15N values of soil N. We conclude that species limited by the same nutrient may coexist by drawing on different pools of soil N in a nutrient-deficient environment. The differences among life-forms decrease with increasing N availability. The different levels of δ15N are associated with different nitrogen concentrations in leaves, Picea having a lower N concentration (0.62 mmol g−1) than Vaccinium (0.98 mmol g−1) or Calamagrostis (1.33 mmol g−1). An extended vector analysis by Timmer and Armstrong (1987) suggests that N is the most limiting element for Picea in this habitat, causing needle yellowing at N concentrations below 0.5 mmol g−1 or N contents below 2 mmol needle−1. Increasing N supply had an exponential effect on twig and needle growth. Phosphorus, potassium and magnesium are at marginal supply, but no interaction between ammonium supply and needle Mg concentration could be detected. Calcium is in adequate supply on both calcareous and acidic soils. The results are compared with European conditions of excessive N supply from anthropogenic N depositions.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00317862

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AlkaliammingraphitverbindungenProfessor Walter Hieber zum 60. Geburtstage gewidmet (1955)

Rüdorff, W. ; Schulze, E. ; Rubisch, O.

Weinheim : Wiley-Blackwell

Zeitschrift für anorganische Chemie 282 (1955), S. 232-240

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ISSN: 0044-2313

Keywords: Chemistry ; Inorganic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: Bei der Einwirkung von in flüssigem Ammoniak gelöstem Lithium, Natrium, Kalium, Rubidium und Cäsium auf Graphit oder bei der Umsetzung der bekannten Alkaligraphitverbindungen mit flüssigem NH3 entstehen sehr reaktionsfähige Graphitverbindungen, in denen Metallatome und NH3-Molekeln in das Gitter eingelagert sind. Es konnten bisher dargestellt werden: eine blaue Verbindung mit der angenäherten Zusammensetzung C12Me(NH3)2 und der Struktur einer 1. Stufe, sowie eine alkaliärmere, schwarze Verbindung, etwa C28Me(NH3)2 mit der Struktur einer 2. Stufe.Lithium, gelöst in Methylamin, gibt mit Graphit eine blaue 1. Stufe mit der Idealformel C12Li(CH3NH2)2.Durch die Einlagerung vergrößert sich der Abstand benachbarter C-Ebenen im Graphit von 3,35 auf 6,6 kX bei allen Ammoniakaten und auf 6,9 kX bei der Methylaminverbindung.

Additional Material: 2 Ill.