Spatial heterogeneity and environmental predictors of permafrost region soil organic carbon stocks

Large stocks of soil organic carbon (SOC) have accumulated in the Northern
Hemisphere permafrost region, but their current amounts and future fate
remain uncertain. By analyzing dataset combining >2700 soil
profiles with environmental variables in a geospatial framework, we
generated spatially explicit estimates of permafrost-region SOC stocks,
quantified spatial heterogeneity, and identified key environmental
predictors. We estimated that 1014+194−175 Pg C are
stored in the top 3 m of permafrost region soils. The greatest
uncertainties occurred in circumpolar toe-slope positions and in flat
areas of the Tibetan region. We found that soil wetness index and
elevation are the dominant topographic controllers and surface air
temperature (circumpolar region) and precipitation (Tibetan region) are
significant climatic controllers of SOC stocks. Our results provide first
high-resolution geospatial assessment of permafrost region SOC stocks and
their relationships with environmental factors, which are crucial for
modeling the response of permafrost affected soils to changing climate.