• 研究报告 •

### 青藏高原中东部表土轻组碳氮含量分布及其影响因素

1. 1天津大学表层地球系统科学研究院， 天津 300072； 2天津师范大学地理与环境科学学院， 天津 300387;  3天津师范大学天津市水资源与水环境重点实验室， 天津 300387）
• 出版日期:2020-08-10 发布日期:2021-02-10

### Distribution and impact factors of carbon and nitrogen contents in light fractions of topsoil on the central and eastern Tibetan Plateau.

YANG Xue-mei1,2, YANG An2, XING Wen-cong2, WANG Xiao-xia2, LIU Xiao-long3, Khan M.G. Mostofa1, LI Jun3*

1. (1Institute of SurfaceEarth System Science, Tianjin University, Tianjin 300072, China; 2College of Geography and Environmental Science, Tianjin Normal University, Tianjin 300387, China; 3Tianjin Key Laboratory of Water Resources and Environment, Tianjin Normal University, Tianjin 300387, China).
• Online:2020-08-10 Published:2021-02-10

Abstract: The light fraction (LF) of soil is sensitive for identifying changes in soil due to human activities or environmental changes. To explore the distribution and influencing factors of soil LF content on the central and eastern Tibetan Plateau, we measured the LF, heavy fraction (HF) and its carbon and nitrogen content and C/N ratio of topsoil at different vegetation types. We further analyzed the relationships between the carbon and nitrogen content, C/N ratio of LF and environmental factors. The results showed that the contribution of LF to total soil organic matter was small (2.11%). The content of LF in topsoil at different vegetation types followed the order of forest land > alpine meadow > alpine steppe > desert. The average contents of soil LF organic carbon (LFOC) and HF organic carbon (HFOC) in all sampling sites were 27.23% and 2.39%, respectively, with highest content in the forests (31.73% vs. 2.64%). LFOC was the lowest in desert (24.63%), whilst HFOC was the lowest in alpine meadow (2.30%). The average contents of LF total nitrogen (LFTN) and HF total nitrogen (HFTN) were 1.22% and 0.12%, respectively, being highest in alpine meadow (1.28% vs. 0.12%) and lowest in forests (1.14% vs. 0.10%). The average value of the LF C/N ratio and HF C/N ratio was 27.67 and 11.59. C/N ratio in both LF and HF (36.95 vs. 15.15) was the highest in the forests, whilst was the lowest in LF of alpine meadow (25.45) and in HF of alpine steppe (10.03). These results imply that humification degree of forests is high and the available nitrogen content is low, while an opposite pattern was found for alpine meadows and alpine steppe. The contents and distribution of the LF in topsoil on the central and eastern Tibetan Plateau significantly varied across vegetation type, while soil pH is the most important environmental factor affecting LF carbon and nitrogen contents.