黄河源高寒湿地有机碳组分对不同退化程度的响应

Responses of Soil Organic Carbon Component on Different Degrees of Degradation of Alpine Wetland in the Source of Yellow River

本研究以黄河源区玛沁县大武滩不同退化高寒湿地为研究对象,分层采集冻融丘和丘间土层样品,分析土壤有机碳组分的变化及其与土壤因子的关系。结果表明:冻融丘和丘间各层轻组分有机碳、重组分有机碳、可溶性有机碳、微生物碳含量随着退化程度的加剧下降,且在未退化与轻度退化、重度退化样地冻融丘0~10 cm土层间差异显著(P<0.05),冻融丘对退化比丘间敏感;土壤重组分有机碳含量占总有机碳含量的94.00%以上,是有机碳的最主要组成部分;随着退化程度的加剧,冻融丘和丘间土壤微生物碳占比显著减少(P<0.05),对高寒湿地退化的响应敏感;土壤含水量与有机碳、轻组分有机碳、重组分有机碳、可溶性有机碳和微生物碳含量呈正相关关系。综上所述,高寒湿地退化导致有机碳组分减少,重组分有机碳含量和占比可作为反映土壤有机碳库变化的关键指标,微生物碳含量和占比可作为反映高寒湿地退化的关键指标,均可为高寒湿地生态系统碳库和恢复机理的研究提供数据支撑。

Different layers of soil were taken from frozen-thawing mounds as well as among them in alpine wetland with different degrees of degradation in Maqin Dawutan,the source of Yellow River.The soil organic carbon component and its relationship with soil factors were determined.Results in this study showed that the organic carbon component(light fraction organic carbon,heavy fraction organic carbon,dissolved organic carbon,microbial biomass carbon)of frozen-thawing mounds as well as among mounds decreased with the aggravation of degradation degree,and was significantly different(P<0.05)in 0~10 cm soil layer between undegraded,mildly degraded and severely degraded sample plots.The soil organic carbon components of frozen-thawing mounds were more sensitive than that among mounds.The content of heavy soil organic carbon accounted for more than 94.00%of the total organic carbon,which was the most important component of organic carbon.With the aggravation of degradation degree,the proportion of microbial biomass carbon in frozen-thawing mounds as well as among mounds decreased significantly(P<0.05),and the proportion of soil microbial biomass carbon was sensitive to the degradation of alpine wetland.Soil water content positively correlated with soil organic carbon,light fraction organic carbon,heavy fraction organic carbon,dissolved organic carbon and microbial biomass carbon.In conclusion,the degradation of alpine wetlands leads to a decrease in organic carbon components.The content and proportion of heavy fraction organic carbon can be used as key indicators to reflect changes of soil organic carbon pools,and the content and proportion of microbial biomass carbon can be used as key indicators to reflect the degradation of alpine wetlands.This can provide data support for research on the carbon storage and restoration mechanism of alpine wetland ecosystem.