Plant and Soil

, Volume 355, Issue 1, pp 75–86

Changes in microbial activities and biomasses over a forest floor gradient in C-to-N ratio

  • Lars Ola Nilsson
  • Håkan Wallander
  • Per Gundersen
Regular Article

DOI: 10.1007/s11104-011-1081-7

Cite this article as:
Nilsson, L.O., Wallander, H. & Gundersen, P. Plant Soil (2012) 355: 75. doi:10.1007/s11104-011-1081-7

Abstract

Background and aims

Under chronically elevated N deposition, N retention mainly occur at high soil C-to-N ratio. This may be mediated through soil microbes, such as ectomycorrhizal (EM) fungi, saprotrophic fungi and bacteria, and the aim of this study was to evaluate the relationship between soil microbes and forest floor C-to-N ratios.

Methods

Soil samples from 33 Norway spruce (Picea abies (L.) H. Karst) forests in Denmark and southern Sweden in a forest floor C-to-N ratio gradient (ranging from 14 to 35) were analysed regarding the content of phospholipid fatty acids (PLFAs) to estimate their soil microbial community composition and the relative biomasses of different microbial groups. The relation of EM biomass to total fungal biomass was estimated as the loss of the fungal PLFA 18:2ω6,9 during incubation of soils and the production of EM mycelia was estimated using fungal in-growth mesh bags. The soil microbial variables were correlated to forest floor C-to-N ratio, NO3- leaching, soil pH and stand age.

Results

Fungal proportions of microbial biomass, EM to total fungi and EM mycelial production were all positively related to C-to-N ratio, while NO3- leaching was negatively related to C-to-N ratio.

Conclusions

Both EM and saprotrophic fungi change with forest floor C-to-N ratios and appear to play a central role in N retention in forest soil. A better understanding of the mechanisms behind this process may be revealed if the role of recalcitrant fungal metabolites for N retention (and soil C sequestration) can be identified. Research along this line deserves further studies.

Keywords

Ectomycorrhizal fungiExternal myceliaC-to-N ratioMicrobial biomassNitrate leachingNorway sprucePhospholipid fatty acids (PLFA)

Copyright information

© Springer Science+Business Media B.V. 2011

Authors and Affiliations

  • Lars Ola Nilsson
    • 1
    • 3
  • Håkan Wallander
    • 2
    • 4
  • Per Gundersen
    • 1
  1. 1.Danish Centre for Forest, Landscape and PlanningUniversity of CopenhagenCopenhagenDenmark
  2. 2.Department of Biology, Microbial ecology groupLund UniversityLundSweden
  3. 3.Norwegian Institute for Agricultural and Environmental ResearchSvanvikNorway
  4. 4.Microbial EcologyLund UniversityLundSweden