Abstract:This study was oriented to characterize the evolution of soil nitrogen composition with degradation of alpine marshy meadow wetland of Gahai.The contents of total N,available N,microbial biomass N and nitrite N content were tested from 4 succession stages,including(Undegraded(UD),lightly degraded(LD),moderately degraded(MD) and heavy degraded(HD) of the different soil layers(0~10 cm、10~20 cm 、20~30cm和30~40 cm).The results showed that:In terms of average contents of total N,available N,microbial biomass N and nitrite N,the four types of wetlands exhibited an order of UD>LD >MD >HD in 0~40 cm layer soils.With UD turning into HD,the contents of soil total N,available N,microbial biomass N and nitrite N in 0~10 cm and 30~40 cm were decreased significantly or by 15.28% and 2.33%,12.13% and 8.41%,13.94%,10.58%,22.69% and 51.70%,respectively(P<0.05).Regression analysis results showed that:The contents of N were significantly negativelyrelated with soil depth.The R2of soil N component was larger than 0.88,except the total N.This indicated that nitrogen contents were significantly decreased in 0~10 cm with wetland degradation,but the decreased trend gradually tends to be stable with the increasing of soil layer.