尕海湿地退化演替过程中土壤氮组分的变化特征

Variation characteristics of soil nitrogen in the process of degraded succession of Gahai wetland

为了研究尕海沼泽化草甸湿地随退化程度的加剧氮素的分布特征,对该区域4个退化演替阶段,即未退化(UD)、轻度退化(LD)、中度退化(MD)和重度退化(HD)的4个土层深度(0~10 cm、10~20 cm、20~30cm和30~40 cm)土壤的全氮、速效氮、微生物量氮及亚硝态氮含量进行了测定。结果表明:不同阶段0~40 cm土层全氮、亚硝态氮、微生物量氮和速效氮含量均值均按照UD、LD、MD、HD的顺序降低。0~10 cm和30~40 cm土层HD的全氮、速效氮含量分别显著低于UD 15.28%和2.33%、12.13%和8.41%;UD的微生物量氮和亚硝态氮含量分别显著高出HD 13.94%和10.58%、22.69%和51.70%(P<0.05)。回归分析土壤氮素含量与土层深度之间呈线性负相关关系,除全氮外,其他氮组分含量与土层深度的R^(2)均大于0.88。由此说明湿地退化显著降低了0~10 cm土层湿地土壤的氮素含量,但这种降低趋势随着土层加深逐渐趋于稳定。

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.