Chemical changes in organic matter after fungal colonization in a nitrogen fertilized and unfertilized Norway spruce forest

César Nicolás, Juan P. Almeida, Magnus Ellström, Adam Bahr, Sharon E. Bone, Nicholas P. Rosenstock, John R. Bargar, Anders Tunlid, Per Persson, Håkan Wallander

Research output: Contribution to journalArticlepeer-review


Background and aims: Decomposition and transformation of organic matter (OM) in forest soils are conducted by the concomitant action of saprotrophic and mycorrhizal fungi. Here, we examine chemical changes in OM after fungal colonization in nitrogen fertilized and unfertilized soils from a Norway spruce forest. Methods: Sand-filled bags amended with composted maize leaves were placed in the forest soil and harvested after 17 months. Infrared and near edge X-ray absorption fine structure spectroscopies were used to study the chemical changes in the OM. Fungal community composition of the bags was also evaluated. Results: The proportion of ectomycorrhizal fungi declined in the fertilized plots, but the overall fungal community composition was similar between N treatments. Decomposition of the OM was, independently of the N level or soil horizon, accompanied by an increase of C/N ratio of the mesh-bag content. Moreover, the proportions of carboxylic compounds in the incubated OM increased in the mineral horizon, while heterocyclic-N compounds decreased, especially in unfertilized plots with higher N demand from the trees. Conclusions: Our results indicate that more oxidized organic C and less heterocyclic-N proportions in the OM remain after fungal colonization in the mineral layers, and suggest that ectomycorrhizal fungi transfer less heterocyclic-N from the mesh bags to the host trees under high N levels.

Original languageEnglish
Pages (from-to)113-126
JournalPlant and Soil
Issue number1-2
Early online date2017 Jul 8
Publication statusPublished - 2017 Oct

Subject classification (UKÄ)

  • Microbiology
  • Ecology

Free keywords

  • Fungal community composition
  • Infrared spectroscopy
  • Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy
  • Nitrogen fertilization
  • Norway spruce forest
  • Organic matter decomposition


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