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 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.

Automated summary

Large stocks of organic carbon have accumulated in the permafrost region of the Northern Hemisphere, with estimated amounts in the top 3 meters of soil. Analysis of over 2700 soil profiles revealed that soil wetness index and elevation are key topographic controllers, while surface air temperature and precipitation play significant roles in determining SOC stocks. The study's high-resolution geospatial assessment provides important insights for modeling the response of permafrost-affected soils to climate change.