近30 a陕西土壤有机碳的时空变化特征及影响因素

Temporal and Spatial Variations of Soil Organic Carbon and the Influencing Factors in Shaanxi Province in Recent 30 Years

土壤有机碳(SOC)动态变化对土壤质量演变和全球碳循环具有极其重要的指示意义,因此有必要对区域SOC库的时空分布变化和影响因素进行研究.分别收集陕西省1985~2015年近30 a共540个土壤剖面信息及其环境变量数据,使用单因素方差分析和路径分析法探究陕西省SOC含量的时间和空间分布特征以及SOC含量变化的影响因素.结果表明,1985年和2015年陕西省SOC含量在空间分布上表现为:关中最高,陕南次之,且都显著高于陕北.自1985~2015年,陕南SOC含量上升幅度最大,为21.28%,关中上升了15.33%,而陕北SOC含量小幅度下降,降幅为10.23%,主要发生在60~80 cm和80~100 cm的深层土壤.与1985年相比,2015年陕西省0~100 cm各土层SOC含量增幅的变化范围为3.21%~29.39%.1985年和2015年各土壤类型中SOC含量最高的土壤类型分别为暗棕壤和棕壤.与1985年相比,2015年SOC含量增幅最大的土壤类型为粗骨土,其次为新积土.相关分析及路径分析结果表明,SOC含量与海拔显著正相关,与年平均降水量、归一化植被指数和全氮含量极显著正相关;与曲率、容重和pH极显著负相关.全氮含量是影响SOC含量的主控因素.研究结果可为区域内未来的碳管理措施提供参考.

Soil organic carbon(SOC)variation is a significant indicator for the soil quality dynamic and global carbon cycle.Therefore,it is necessary to study the regional temporal and spatial distribution of SOC pool and the influencing factors.In this study,a total of 540 soil data and environmental variables were collected from Shaanxi Province during a 30-year period from 1985 to 2015,and univariate analysis of variance and path analysis were used to explore the temporal and spatial distribution characteristics of SOC content and the influencing factors of SOC change.The results showed that the SOC contents of Shaanxi Province in both 1985 and 2015 were the highest in central Shaanxi,followed by those in southern Shaanxi,and they were significantly higher than those in northern Shaanxi.From 1985 to 2015,the increase in SOC in southern Shaanxi was the highest(21.28%),and that in central Shaanxi was 15.33%.The content of SOC in northern Shaanxi was decreased by 10.23%,caused by significant decrements in the bottom horizons of 60-80 cm and 80-100 cm.Compared with that in 1985,the increases in SOC content in the 0-100 cm soil profile(with every 20 cm as a horizon)ranged from 3.21% to 29.39% in 2015.The increase in SOC content of skeletal soils was largest,followed by that of alluvial soils.Correlation analysis and path analysis showed that SOC content was positively correlated with altitude,average annual precipitation,normalized vegetation index,and total nitrogen content and was in significant negative correlation with curvature,bulk density,and pH.Total nitrogen content was the main controlling factor affecting SOC content.The results of the study can provide reference for future carbon management measures in the region.