Recently,the degradation of permafrost and marsh environments in the Da and Xiao Hinggan Mountains has become a great concern as more human activities and pronounced climate warming were observed during the past 30 years and projected for the near future.The distribution patterns and development mechanisms of the permafrost and marshes have been examined both in theories and in field observations,in order to better understand the symbiosis of permafrost and marshes.The permafrost and marshes in the Da and Xiao Hinggan Mountains display discernible zonations in latitude and elevation.The marsh vegetation canopy,litter and peat soil have good thermal insulation properties for the underlying permafrost,resulting in a thermal offset of 3℃ to 4℃ and subsequently suppressing soil temperature.In addition,the much higher thermal conductivity of frozen and ice-rich peat in the active layer is condu-cive to the development or in favor of the protection of permafrost due to the semi-conductor properties of the soils overlying the permafrost.On the other hand,because permafrost is almost impervious,the osmosis of water in marsh soils can be effectively reduced,timely providing water supplies for helophytes growth or germination in spring.In the Da and Xiao Hinggan Mountains,the permafrost degradation has been accelerating due to the marked climate warming,ever increasing human activities,and the resultant eco-environmental changes.Since the permafrost and marsh envi-ronments are symbiotic and interdependent,they need to be managed or protected in a well-coordinated and integrated way.
