A typical feature of the boreal forest landscape is a gradient from dry to wet sites, with
associated increases in the depth of the soil organic layers. In this study, the coupled
ecosystem–soil biogeochemistry model GUESS–ROMUL is used to explore how the specific
features of soil organic matter decomposition and vegetation dynamics account for an
observed difference between the soils formed under contrasting moisture conditions. Two
sites, one mesic and one mesic-to-wet, representative of the natural forest in Northern Sweden,
are simulated. In addition to the assumptions underlying the GUESS–ROMUL model,
it is assumed that the fire frequency was higher at the mesic site. The model shows that
with a natural fire regime, the soil organic layers at the mesic-to-wet site store 6.0 kg Cm−2
compared to 3.1 kg Cm−2 at the mesic site. Forty-seven percent of the difference between
the sites in this respect is explained by suppressed decomposition under higher moisture
conditions, 37% by the decreased litter input into the soil (more frequently disturbed ecosystems
have lower productivity) and 16% by direct consumption of the forest floor in fires. It
is predicted that due to anthropogenic fire suppression the organic soil layers of mesic sites
will, in the future, sequester carbon at an average rate of 0.0103 kg Cm−2 year−1 and have
an equilibrium storage capacity of 5.4 kg Cm−2. For the mesic-to-wet site, the model predicts
an extremely slow sequestration rate of 0.0022 kg Cm−2 year−1. The effect of increased
precipitation on the carbon storage at the landscape level is also investigated
A typical feature of the boreal forest landscape is a gradient from dry to wet sites, with
associated increases in the depth of the soil organic layers. In this study, the coupled
ecosystem–soil biogeochemistry model GUESS–ROMUL is used to explore how the specific
features of soil organic matter decomposition and vegetation dynamics account for an
observed difference between the soils formed under contrasting moisture conditions. Two
sites, one mesic and one mesic-to-wet, representative of the natural forest in Northern Sweden,
are simulated. In addition to the assumptions underlying the GUESS–ROMUL model,
it is assumed that the fire frequency was higher at the mesic site. The model shows that
with a natural fire regime, the soil organic layers at the mesic-to-wet site store 6.0 kg Cm−2
compared to 3.1 kg Cm−2 at the mesic site. Forty-seven percent of the difference between
the sites in this respect is explained by suppressed decomposition under higher moisture
conditions, 37% by the decreased litter input into the soil (more frequently disturbed ecosystems
have lower productivity) and 16% by direct consumption of the forest floor in fires. It
is predicted that due to anthropogenic fire suppression the organic soil layers of mesic sites
will, in the future, sequester carbon at an average rate of 0.0103 kg Cm−2 year−1 and have
an equilibrium storage capacity of 5.4 kg Cm−2. For the mesic-to-wet site, the model predicts
an extremely slow sequestration rate of 0.0022 kg Cm−2 year−1. The effect of increased
precipitation on the carbon storage at the landscape level is also investigated
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