J. Geophys. Res. http://doi.org/hv8 (2012)

Credit: © ISTOCKPHOTO/THINKSTOCK

Vast accumulations of carbon are stored in Arctic and boreal soils, and understanding of the stability of these stocks to climate warming is a key research question being investigated by scientists from many different disciplines. Soil-carbon stability is related to decomposition processes, which are in turn largely determined by soil thermal regime and cannot be simply related to air temperature.

Field measurements report different thermal properties for the snowpack in Arctic tundra (low shrubs, sedge and moss dominated) and taiga (coniferous and mixed forest dominated) regions. Isabelle Gouttevin, from AgroParisTech/LGGE, France, and co-authors used a modelling approach to quantify the potential influence of these different snow thermal properties on soil thermal regime and terrestrial soil-carbon distribution across the pan-Arctic continental area.

They found that higher insulation by snow in taiga areas induces warmer soil temperatures by up to 12 °C, and up to 4 °C in the summer (at 50 cm depth). These soil temperature changes have implications for soil-carbon stock estimates, which are found to be reduced by 8% across the Arctic continental area when vegetation-induced variations of snow thermal properties are accounted for. Soil-carbon differences are accounted for by complex ecosystem interactions that reduce productivity overall and enhance soil microbial decomposition.