Oecologia

, Volume 147, Issue 1, pp 96–107

Contrasting patterns of soil N-cycling in model ecosystems of Fennoscandian boreal forests

  • Mona N. Högberg
  • David D. Myrold
  • Reiner Giesler
  • Peter Högberg
Ecosystem Ecology

DOI: 10.1007/s00442-005-0253-7

Cite this article as:
Högberg, M.N., Myrold, D.D., Giesler, R. et al. Oecologia (2006) 147: 96. doi:10.1007/s00442-005-0253-7

Abstract

The low plant productivity of boreal forests in general has been attributed to low soil N supply and low temperatures. Exceptionally high productivity occurs in toe-slope positions, and has been ascribed to influx of N from surrounding areas and higher rates of soil N turnover in situ. Despite large apparent natural variations in forest productivity, rates of gross soil N mineralization and gross nitrification have never been compared in Fennoscandian boreal forests of contrasting productivity. We report contrasting patterns of soil N turnover in three model ecosystems, representing the range in soil C-to-N ratios (19–41) in Fennoscandian boreal forests and differences in forest productivity by a factor close to 3. Gross N mineralization was seven times higher when soil, microbial, and plant C-to-N ratios were the lowest compared to the highest. This process, nitrification and potential denitrification correlated with inorganic, total and microbial biomass N, but not microbial C. There was a constant ratio between soil and microbial C-to-N ratio of 3.7±0.2, across wide ratios of soil C-to-N and fungi-to-bacteria. Soil N-cycling should be controlled by the supplies of C and N to the microbes. In accordance with plant allocation theory, we discuss the possibility that the high fungal biomass at high soil C-to-N ratio reflects a particularly high supply of plant photosynthates, substrates of high-quality C, to mycorrhizal fungi. Methods to study soil N turnover and N retention should be developed to take into account the impact of mycorrhizal fungi on soil N-cycling.

Keywords

C-to-N stoichiometry Forest productivity Gross N turnover Mycorrhizal fungi 

Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  • Mona N. Högberg
    • 1
  • David D. Myrold
    • 2
  • Reiner Giesler
    • 1
    • 3
  • Peter Högberg
    • 1
  1. 1.Department of Forest EcologySwedish University of Agricultural Sciences, SLUUmeåSweden
  2. 2.Department of Crop and Soil ScienceOregon State UniversityCorvallisUSA
  3. 3.Climate Impact Research Centre, Department of Ecology and Environmental ScienceUmeå UniversityUmeåSweden

Personalised recommendations