The thermal conductivity of vegetation ground covers in permafrost areas

Abstract Cold biomes are characterized by bryophyte-dominated vegetation, which helps regulate soil temperature by altering thermal conductivity based on moisture content. However, information on the thermal properties of vegetation ground covers in permafrost areas, particularly in their frozen state, remains limited. This study aims to fill this gap by investigating the thermal conductivity of various moss and lichen species collected from Northern Manitoba’s Hudson Bay lowlands, using both field and laboratory measurements. The results show that, in unfrozen conditions, thermal conductivity increases linearly with volumetric water content. In frozen samples, an exponential relationship was observed, indicating an increase in conductivity as water turns to ice. We derived empirical equations to describe these relationships and validated them using one-dimensional thermal modeling at instrumented permafrost sites. We also tested the transferability of our approach at a comparative site in the Yamal region and explored the thermal impacts of vegetation removal. The findings highlight the importance of including vegetation ground cover properties in permafrost thermal modeling and provide a practical framework for quantifying their effects under both natural and disturbed conditions.