典型绿洲不同土壤类型有机碳含量及其稳定碳同位素分布特征

Spatial Variation of Soil Organic Carbon and Stable Isotopes in Different Soil Types of a Typical Oasis

土壤有机碳及其稳定同位素组成反映了生态系统碳循环的关键信息,对研究全球变化下陆地生态系统碳动态及碳资源的可持续发展具有重要意义.本研究以阿拉尔绿洲4种土壤类型为研究对象,测定不同深度土壤有机碳(SOC)含量和δ^(13)C值,探讨不同土壤类型有机碳分布、δ^(13)C_(SOC)丰度差异及其与土壤环境因子的关系.结果表明:(1)土壤整体有机碳含量由高到低依次为灌漠土、棕漠土、盐土、风沙土,且在表层(0~20 cm层)具有较大值;δ^(13)C_(SOC)变化范围在-26‰^-23‰,表层(0~20 cm)由正趋负为盐土>风沙土>灌漠土>棕漠土.(2)土壤有机碳含量受土壤类型、深度及其交互作用极显著影响,δ^(13)C_(SOC)受土壤类型、交互作用显著影响;进一步交互效应检验中土壤有机碳受因素水平影响极强,同位素相对较弱.(3)冗余分析发现土壤有机碳与土壤无机碳、全氮、土壤含水量、容重均存在显著或极显著正相关关系,与C/N具有显著负相关关系;δ13CSOC与电导率存在显著正相关关系,与土壤无机碳、土壤含水量均存在极显著负相关关系.土壤环境因子的重要性排序为土壤含水量>土壤无机碳>容重>全氮>C/N>电导率>pH.分析得出土壤有机碳及其同位素在不同土壤类型中呈现出不同变化规律,其土壤类型的效应强于土壤深度,受土壤含水量影响最甚.

Soil organic carbon（ SOC） and its stable isotope composition reflect important information on ecosystem carbon cycle.Under the background of global change,it is of great significance to study carbon dynamics and sustainable development of carbon resources in terrestrial ecosystems. In this study,four soil types in Alar oasis were studied to determine SOC content and δ^13C value at different layers,and the differences of δ^13C（SOC） abundance and its relationship with soil environmental factors were also discussed. Three main outcomes were drawn from the results.（1）The total organic carbon（ TOC） content of the soil was in the order of irrigated desert soil 〉brown desert 〉soil saline soil 〉aeolian sandy soil,and had a higher value in the surface layer（ 0-20 cm layer）; δ^13C（SOC） ranged from-26‰--23‰,the surface layer（ 0-20 cm） was in the order saline soil 〉aeolian sandy soil 〉irrigated desert soil 〉brown desert soi.（2） Both SOC and δ^13C（SOC） were significantly affected by soil type and their interaction,and by soil depth. Furthermore,the effect test of interaction indicated that SOC was significantly impacted by environmental factors,but the impact on δ^13C（SOC） was relatively weak.（3） The results of redundancy analysis showed that SOC had a significant or extremely significant positive correlation with soil inorganic carbon,total nitrogen,soil water content and bulk density,and had a significant negative correlation with C/N. There was also a significant positive correlation between δ^13C（SOC） and conductivity,and in addition,δ^13C（SOC） was negatively correlated with soil inorganic carbon and soil water content. The analyses showed that SOC and its isotopes changed with soil types,and that the effect of soil type was stronger than that of soil depth,which was mainly determined by soil moisture content.