Vegetation impact on the thermal regimes of the active layer and near-surface permafrost in the Greater Hinggan Mountains, Northeastern China

摘要

The ground temperature and active layer are greatly influenced by vegetation in the Greater Hinggan Mountains in Northeastern China.However,vegetation,as a complex system,is difficult to separate the influence of its different components on the ground thermal regime.In this paper,four vegetation types,including a Larix dahurica–Ledum palustre var.dilatatum–Bryum forest(P1),a L.dahurica–Betula fruticosa forest(P2),a L.dahurica–Carex tato forest(P3) in the China Forest Ecological Research Network Station in Genhe,and a Carex tato swamp(P4) at the permafrost observation site in Yitulihe,have been selected to study and compare their seasonal and annual influence on the ground thermal regime.Results show that the vegetation insulates the ground resulting in a relatively high ground temperature variability in the Carex tato swamp where there are no tree stands and shrubs when compared with three forested vegetation types present in the area.Vegetation thickness,structure,and coverage are the most important factors that determine the insulating properties of the vegetation.In particular,the growth of ground cover,its water-holding capacity and ability to intercept snow exert a significant effect on the degree of insulation of the soil under the same vegetation.