Journal of Geographical Sciences ›› 2018, Vol. 28 ›› Issue (1): 15-30.doi: 10.1007/s11442-018-1456-2

• Research Articles • Previous Articles     Next Articles

Latitudinal patterns and influencing factors of soil humic carbon fractions from tropical to temperate forests

Li XU1,3(), Chunyan WANG4, Jianxing ZHU1,3, Yang GAO1, Meiling LI1, Yuliang LV2, Guirui YU1, Nianpeng HE1,3,*()   

  1. 1. Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China
    2. College of Geographical Science, Southwest University, Chongqing 400715, China
    3. College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100190, China
    4. Branch of Experimental School of Beihang University, Beijing 100191, China
  • Received:2017-01-10 Accepted:2017-08-23 Online:2018-01-10 Published:2018-01-10
  • Contact: Nianpeng HE;
  • About author:

    Author: Xu Li, PhD, specialized in soil carbon storage and sequestration. E-mail:

    The authors Xu Li and Wang Chunyan contributed equally to this work.

  • Supported by:
    National Key Research Project of China, No2016YFC0500202;STS of Chinese Academy of Sciences, No.KFJ- SW-STS-167;National Natural Science Foundation of China, No.31290221, No.31570471;Youth Innovation Research Team Project, NoLENOM2016Q0005


Soil humic carbon is an important component of soil organic carbon (SOC) in terrestrial ecosystems. However, no study to date has investigated its geographical patterns and the main factors that influence it at a large scale, despite the fact that it is critical for exploring the influence of climate change on soil C storage and turnover. We measured levels of SOC, humic acid carbon (HAC), fulvic acid carbon (FAC), humin carbon (HUC), and extractable humus carbon (HEC) in the 0-10 cm soil layer in nine typical forests along the 3800-km North-South Transect of Eastern China (NSTEC) to elucidate the latitudinal patterns of soil humic carbon fractions and their main influencing factors. SOC, HAC, FAC, HUC, and HEC increased with increasing latitude (all P<0.001), and exhibited a general trend of tropical < subtropical < temperate. The ratios of humic C fractions to SOC were 9.48%-12.27% (HAC), 20.68%-29.31% (FAC), and 59.37%-61.38% (HUC). Climate, soil texture, and soil microbes jointly explained more than 90% of the latitudinal variation in SOC, HAC, FAC, HEC, and HUC, and interactive effects were important. These findings elucidate latitudinal patterns of soil humic C fractions in forests at a large scale, and may improve models of soil C turnover and storage.

Key words: humic acid carbon, humin, latitude, pattern, soil organic carbon, NSTEC