长江源区布曲流域土壤有机碳分布特征及其影响因素

Distribution characteristics and influencing factors of soil organic carbon in Buqu catchment in the source region of the Yangtze River, China

基于长江源区布曲流域23个采样点的138个土壤样品,分析了土壤有机碳的分布特征,并探讨1 m以内土壤有机碳含量的影响因素。结果表明,长江源区布曲流域0~10 cm、10~20 cm、20~30 cm、30~40 cm、40~50 cm和50~100 cm的6层土壤有机碳含量的平均值±标准差分别为(10.23±4.84) g·kg^(-1)、(10.18±5.19)g·kg^(-1)、(9.34±5.20)g·kg^(-1)、(9.04±4.41)g·kg^(-1)、(8.01±4.74)g·kg^(-1)、(9.40±4.67)g·kg^(-1),其随土壤深度增加而降低(R^(2)=0.511)。研究区土壤有机碳含量与海拔并非线性相关(P>0.05),而是在4 700~5 100 m的海拔范围内,随海拔的升高而增加,然后在5 000~5 100 m海拔处达到最大值后降低。土壤有机碳含量与pH值呈现极显著的负相关(P<0.01),与碳氮比呈现极显著的正相关(P<0.01),与体积含水量呈现显著的正相关关系(P<0.05),而与年均气温、年均降水量、全氮、全磷、全钾、无机碳含量、阳离子交换量、容重和黏粒含量的相关性不显著(P>0.05),表明长江源区布曲流域1 m以内土壤有机碳含量的主要相关因素是土壤的pH值、碳氮比和体积含水量。研究结果可以为长江源区布曲流域土壤碳循环的研究提供基础数据和科学依据。

We collected 138 soil samples from 23 sampling sites in the Buqu catchment, the source region of the Yangtze River, China. We examined the distribution pattern of soil organic carbon(SOC), and further discussed the possible influencing factors of SOC content within 1 m. The results showed SOC contents in the 0~10, 10~20, 20~30, 30~40, 40~50 and 50~100 cm layers were(10.23±4.84),(10.18±5.19),(9.34±5.20),(9.04±4.41),(8.01±4.74),(9.40±4.67) g·kg^(-1), respectively. SOC content decreased with the increasing soil depth(R^(2)=0.511). There was no significant linear relationship between SOC content and altitude(P>0.05).With the increasing elevation, SOC content was gradually increased between 4 700 to 5 100 m, while the SOC then gradually declined with elevation from 5 100 to 5 250 m. SOC content was negatively correlated with soil pH value(P<0.01), but positively correlated with C/N ratio(P<0.01). The SOC content was also positively correlated with volume water content(P<0.05), but had no significant correlation with mean annual temperature, mean annual precipitation, total nitrogen, total phosphorus, total kalium, inorganic carbon content, cation exchange capacity, bulk density and clay content(P>0.05). Therefore, soil pH value, C/N ratio and volumetric water content were the main factors that were closely associated with the SOC content within 1 m depths. The results can provide a useful dataset for studying soil carbon cycle in the Buqu catchment, the source region of the Yangtze River, China.