Chin J Plant Ecol ›› 2022, Vol. 46 ›› Issue (11): 1422-1431.DOI: 10.17521/cjpe.2022.0082

Special Issue: 生态化学计量 青藏高原植物生态学:植物-土壤-微生物

• Research Articles • Previous Articles    

Soil carbon, nitrogen, and phosphorus stoichiometry along an altitude gradient in shrublands in Pailugou watershed, China

MOU Wen-Bo1, XU Dang-Hui1,*(), WANG Xie-Jun1, JING Wen-Mao2, ZHANG Rui-Ying1, GU Yu-Ling1, YAO Guang-Qian1, QI Shi-Hua1, ZHANG Long1, GOU Ya-Fei1   

  1. 1State Key Laboratory of Grassland Agro-ecosystems, School of Ecology, Lanzhou University, Lanzhou 730000, China
    2Academy of Water Resources Conservation Forests in Qilian Mountains of Gansu Province, Zhangye, Gansu 734099, China
  • Received:2022-03-07 Accepted:2022-07-01 Online:2022-11-20 Published:2022-09-06
  • Contact: *XU Dang-Hui(
  • Supported by:
    The National Natural Science Foundation of China(32171611);The Natural Science Foundation of Gansu Province(22JR5RA454);The Second Tibetan Plateau Scientific Expedition and Research Program (STEP)(2019QZKK0301)


Aims The study of the spatial distribution pattern of soil nutrient stoichiometry along the altitude gradient is helpful to clarify the status of nutrient limitation in the mountainous ecosystems, to reveal the potential influencing factors to nutrient limitation, and to provide a scientific basis for regional ecological protection and vegetation restoration.
Methods The sampling plots were established along an altitude gradient from 3 100 m to 3 700 m in Pailugou watershed of the Qilian Mountains. Soil samples from 0-10 and 10-20 cm layers were collected separately to analyze the distribution of soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP) contents, and stoichiometric characteristics among different altitude and soil layers. Correlations between these nutrient characteristics and climatic factors, aboveground biomass, and soil pH were analyzed.
Important findings Results showed that: (1) Soil nutrients were concentrated on the soil surface and decreased with soil depth. The SOC and TN contents increased initially and then decreased as altitude increased. Soil TP content increased with increasing altitude. (2) Soil N:P increased from 3 100 m to 3 400 m, reached the maximum value at 3 400 m, and then decreased with increasing altitude and soil N:P was less than 14, suggesting an increase in N limitation along the altitude gradient. The C:P in soil was lower at high altitude than that at medium or low altitude, while C:N decreased with increasing altitude. (3) SOC content was positively correlated with TN content and negatively correlated with TP content. TN and TP content had no significant correlation. (4) Mean air temperature and total precipitation in the growing season showed positive correlation with SOC content and C:N:P, negative correlation with TP content, and no correlation with TN content. SOC and TN content had positive correlations with the aboveground biomass of shrublands. Soil pH was negatively correlated with TP content, but did not affect SOC and TN content significantly. Our results indicate that the productivity of alpine shrublands in the watershed was mainly limited by N and an appropriate amount of N application could alleviate the limitation.

Key words: altitude gradient, soil nutrient, stoichiometry, climatic factor, Qilian Mountains, Pailugou watershed