Slow response of soil organic matter to the reduction in atmospheric nitrogen deposition in a Norway spruce forest

verfasst von

Nicole Dörr, Klaus Kaiser, Robert Mikutta, Georg Guggenberger

Abstract

Global nitrogen (N) deposition rates in terrestrial environments have quadrupled since preindustrial times, causing structural and functional changes of ecosystems. Different emission reduction policies were therefore devised. The aim of our study was to investigate if, and over what timescale, processes of soil organic matter (OM) transformation respond to a decline in atmospheric N deposition. A N-saturated spruce forest (current N deposition: 34 kg ha^-1 yr^-1; critical N load: 14 kg ha^-1 yr^-1), where N deposition has been reduced to 11.5 kg ha^-1 yr^-1 since 1991, was studied. Besides organic C and organic and inorganic N, noncellulosic carbohydrates, amino sugars and amino acids were determined. A decline in organic N in litter indicated initial effects at plant level. However, there were no changes in biomarkers upon the reduction in N deposition. In addition, inorganic N was not affected by reduced N deposition. The results showed that OM cycling and transformation processes have not responded so far. It was concluded that no direct N deposition effects have occurred due to the large amount of stored organic N, which seems to compensate for the reduction in deposited N. Obviously, the time span of atmospheric N reduction (about 14.5 years) is too short compared with the mean turnover time of litter to cause indirect effects on the composition of organic C and N compounds. It is assumed that ecological processes, such as microbial decomposition or recycling of organic N and C, react slowly, but may start within the next decade with the incorporation of the new litter.

Organisationseinheit(en)

Institut für Bodenkunde

Externe Organisation(en)

Martin-Luther-Universität Halle-Wittenberg

Typ

Artikel

Journal

Global change biology

Band

16

Seiten

2990-3003

Anzahl der Seiten

14

ISSN

1354-1013

Publikationsdatum

16.12.2009

Publikationsstatus

Veröffentlicht

Peer-reviewed

Ja

ASJC Scopus Sachgebiete

Globaler Wandel, Umweltchemie, Ökologie, Allgemeine Umweltwissenschaft

Ziele für nachhaltige Entwicklung

SDG 15 – Lebensraum Land

Elektronische Version(en)

https://doi.org/10.1111/j.1365-2486.2009.02148.x (Zugang: Geschlossen)