Abstract

This paper presents an integrated analysis of organic carbon (C) pools in soils and vegetation, within-ecosystem fluxes and net ecosystem exchange (NEE) in three 40-year old Norway spruce stands along a north-south climatic gradient in Sweden, measured 2001-2004. A process-orientated ecosystem model (CoupModel), previously parameterised on a regional dataset, was used for the analysis. Pools of soil organic carbon (SOC) and tree growth rates were highest at the southernmost site (1.6 and 2.0-fold, respectively). Tree litter production (litterfall and root litter) was also highest in the south, with about half coming from fine roots (< 1 mm) at all sites. However, when the litter input from the forest floor vegetation was included, the difference in total litter input rate between the sites almost disappeared (190-233 g C m(-2) year(-1)). We propose that a higher N deposition and N availability in the south result in a slower turnover of soil organic matter than in the north. This effect seems to overshadow the effect of temperature. At the southern site, 19% of the total litter input to the O horizon was leached to the mineral soil as dissolved organic carbon, while at the two northern sites the corresponding figure was approx. 9%. The CoupModel accurately described general C cycling behaviour in these ecosystems, reproducing the differences between north and south. The simulated changes in SOC pools during the measurement period were small, ranging from -8 g C m(-2) year(-1) in the north to +9 g C m(-2) year(-1) in the south. In contrast, NEE and tree growth measurements at the northernmost site suggest that the soil lost about 90 g C m(-2) year(-1).

Keywords

soil carbon; boreal ecosystems; climatic gradient; CoupModel; root litter; dissolved organic carbon

Published in

Biogeochemistry
2008, Volume: 89, number: 1, pages: 7-25
Publisher: SPRINGER

SLU Authors

• Berggren Kleja, Dan

  • Department of Soil Sciences, Swedish University of Agricultural Sciences
    

• Majdi, Hooshang

  • Department of Ecology, Swedish University of Agricultural Sciences
    

• Langvall, Ola

  • Unit for Field-based Forest Research, Swedish University of Agricultural Sciences
    

• Johansson, Maj-Britt

  • Department of Forest Soils, Swedish University of Agricultural Sciences
    

• Ågren, Göran

  • Department of Ecology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Environmental Sciences related to Agriculture and Land-use
Renewable Bioenergy Research


Publication identifier

DOI: https://doi.org/10.1007/s10533-007-9136-9

Permanent link to this page (URI)

https://res.slu.se/id/publ/18625