Chin J Plant Ecol ›› 2023, Vol. 47 ›› Issue (9): 1234-1244.DOI: 10.17521/cjpe.2022.0207

• Research Articles • Previous Articles     Next Articles

Difference of soil carbon sequestration between rhizosphere and bulk soil in a mountain coniferous forest in southwestern China under nitrogen deposition

ZHANG Ying1,2, ZHANG Chang-Hong1,2, WANG Qi-Tong1,*(), ZHU Xiao-Min1, YIN Hua-Jun1   

  1. 1CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization, Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China
    2University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2022-05-19 Accepted:2022-10-31 Online:2023-09-20 Published:2022-11-02
  • Contact: * WANG Qi-Tong(
  • Supported by:
    National Natural Science Foundation of China(31872700);National Natural Science Foundation of China(32171757);Chinese Academy of Sciences Interdisciplinary Innovation Team(xbzg-zdsys-202112)


Aims Due to complex root-soil interactions, the responses of carbon (C) dynamics in the rhizosphere soil to nitrogen (N) deposition may be different from those in bulk soil. However, the potentially different responses of C dynamics between the rhizosphere and bulk soil and their contributions to soil C sequestration under N deposition are still not elucidated.
Methods In this study, a typical subalpine coniferous plantation (Picea asperata) with chronic N addition treatments in southwestern China was selected as the research object. Based on the experimental plots of simulated N deposition (control: 0 kg·hm-2·a-1; N addition: 25 kg·hm-2·a-1), we measured the contents of soil organic carbon and its different physical and chemical fractions. Afterwards, by combining the rhizosphere spatial numerical model, we explored the differences in the C pool size of SOC and its fractions and their relative contribution to SOC pools between the rhizosphere and bulk soil, and further quantified the effects of N addition on soil C sequestration in rhizosphere soil.
Important findings The results showed that: 1) Although the addition of N increased the content of SOC and its physical and chemical components in the rhizosphere and non-rhizosphere at the same time, it only reached a significant level in the rhizosphere. Specifically, the rhizosphere SOC content increased by 23.64% under N addition, in which particulate organic carbon (POC), mineral-associated organic carbon (MAOC), labile carbon (LP-C) and recalcitrant carbon (RP-C) content increased by 19.63%, 18.01%, 30.48% and 15.01%, respectively. 2) The total SOC pool increment of spruce forest (0.88 kg·m-2) was verified with the results of the rhizosphere space numerical model, and the effective rhizosphere extent of the southwest mountain coniferous forest was estimated to be 1.6 mm. Within this extent, N addition increased the SOC stocks of the rhizosphere and bulk soil by 33.37% and 7.38%, contributing to 45.45% and 54.55% of the total SOC pool increment, respectively. Among them, labile C components (POC and LP-C) are the major contributors to rhizosphere SOC accumulation under N addition. These results suggested that the rhizosphere and bulk soil of coniferous forest in southwestern mountainous area had great C sequestration potential under N deposition, and the C sink was more obvious in the rhizosphere soil. Our results highlight the importance of integrating rhizosphere processes into land surface models to accurately predict ecosystem functions in the context of increasing N deposition.

Key words: soil organic carbon, soil carbon fractions, nitrogen deposition, rhizosphere soil, bulk soil, coniferous forest