Abstract

Boreal forest soils retain significant amounts of carbon (C) and nitrogen (N) in purely organic layers, but the regulation of organic matter turnover and the relative importance of leaf litter and root-derived inputs are not well understood.We combined bomb C-14 dating of organic matter with stable isotope profiling for Bayesian parameterization of an organic matter sequestration model. C and N dynamics were assessed across annual depth layers (cohorts), together representing 256 yr of organic matter accumulation. Results were related to ecosystem fertility (soil inorganic N, pH and litter C:N).Root-derived C was estimated to decompose two to 10 times more slowly than leaf litter, but more rapidly in fertile plots. The amounts of C and N per cohort declined during the initial 20 yr of decomposition, but, in older material, the amount of N per cohort increased, indicating N retention driven by root-derived C.The dynamics of root-derived inputs were more important than leaf litter dynamics in regulating the variation in organic matter accumulation along a forest fertility gradient. N retention in the rooting zone combined with impeded mining for N in less fertile ecosystems provides evidence for a positive feedback between ecosystem fertility and organic matter turnover.

Keywords

Bayesian inference; bomb C; decomposition; ecosystem fertility; fungal guilds; leaf- and root-derived C; long-term dynamics; stable isotopes

Published in

New Phytologist
2019, Volume: 221, number: 3, pages: 1492-1502
Publisher: WILEY

SLU Authors

• Kyaschenko, Julia

  • Department of Soil and Environment, Swedish University of Agricultural Sciences
    

• Hagenbo, Andreas

  • Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences
    

• Karltun, Erik

  • Department of Soil and Environment, Swedish University of Agricultural Sciences
    

• Clemmensen, Karina

  • Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences
    

• Lindahl, Björn

  • Department of Soil and Environment, Swedish University of Agricultural Sciences
    

Sustainable Development Goals

Protect, restore and promote sustainable use of terrestrial ecosystems, sustainably manage forests, combat desertification, and halt and reverse land degradation and halt biodiversity loss


UKÄ Subject classification

Soil Science


Publication identifier

DOI: https://doi.org/10.1111/nph.15454

Permanent link to this page (URI)

https://res.slu.se/id/publ/99104