Factors affecting the thickness of permafrost's active layer in Huzhong National Nature Reserve

Taking the Huzhong National Reserve in Great Hing'an Mountain as test object and by the methods of multiple comparison and correlation analysis,this paper studied the thickness of permafrost's active layer in the Reserve and related affecting factors.The results indicated that the thickness of the active layer had complicated relationships with its affecting factors.Soil moisture content,topographic condition and plant communities were the main affecting factors,while the thickness of the active layer also had counter-effects on them.The thickness of the active layer was significantly negatively correlated with surface soil moisture content(P0.001),but positively correlated with slope gradient(P=0.006).For the relationships between active layer's thickness and altitude,no obvious correlation was observed on area scale,though the correlation existed on nearly all transects scale,suggesting that the variance of the active layer's thickness only had regularity on transect scale,but the regularity disappeared on bigger scales.The variance of plant communities also had obvious effects on the thickness of the active layer,and Ledum palustre-Sphagnum community was more helpful for the permafrost conservation.