植物生态学报 ›› 2023, Vol. 47 ›› Issue (9): 1234-1244.DOI: 10.17521/cjpe.2022.0207

• 研究论文 • 上一篇    下一篇

氮沉降下西南山地针叶林根际和非根际土壤固碳贡献差异

张英1,2, 张常洪1,2, 汪其同1,*(), 朱晓敏1, 尹华军1   

  1. 1中国科学院成都生物研究所, 中国科学院山地生态恢复与生物资源利用重点实验室, 生态恢复与生物多样性保育四川省重点实验室, 成都 610041
    2中国科学院大学, 北京 100049
  • 收稿日期:2022-05-19 接受日期:2022-10-31 出版日期:2023-09-20 发布日期:2022-11-02
  • 通讯作者: * 汪其同 ORCID: 0000-0001-9484-3540 (wangqt@cib.ac.cn)
  • 基金资助:
    国家自然科学基金(31872700);国家自然科学基金(32171757);中国科学院“西部之光”交叉团队项目(xbzg-zdsys-202112)

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(wangqt@cib.ac.cn)
  • 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)

摘要:

由于复杂的根系-土壤互作过程, 根际土壤碳(C)动态对氮(N)沉降的响应可能与非根际土壤存在较大差异, 但目前关于N沉降下根际和非根际土壤C动态响应差异及其对土壤C固存的贡献方向与大小尚不明晰。基于此, 该研究以西南山地典型云杉(Picea asperata)人工林为研究对象, 依托研究团队前期建立的模拟N沉降(对照: 0 kg·hm-2·a-1; N添加: 25 kg·hm-2·a-1)实验样地, 分别测定了根际与非根际土壤有机碳(SOC)及其物理组分和化学组分含量, 并借助于根际空间数值模型, 区分和量化了N添加下根际、非根际SOC和不同组分C库含量差异及其对土壤总C增量的贡献效应。研究结果表明: 1)尽管N添加处理同时增加了根际、非根际SOC及其物理、化学组分含量, 但仅在根际区达到显著水平。具体地, 与对照相比, N添加导致根际SOC含量增加了23.64%, 其中颗粒有机碳(POC)、矿物结合态有机碳(MAOC)和活性碳(LP-C)、惰性碳(RP-C)含量分别增加了19.63%、18.01%和30.48%、15.01%。2)通过云杉林总SOC库增量(0.88 kg·m-2)与根际空间数值模型结果相互印证, 确定西南山地针叶林根际有效范围为1.6 mm。在该范围内, N添加导致根际和非根际SOC储量分别增加了33.37%和7.38%, 分别贡献了总SOC库增量的45.45%和54.55%。其中, 活性C组分(POC和LP-C)是N添加下根际SOC累积的主要贡献者。上述结果表明, 西南山地针叶林根际和非根际土壤在N沉降下均发挥重要的土壤C汇作用, 但根际土壤C汇效应更为显著。该研究充分强调了未来N沉降下应将根际C过程纳入森林土壤C循环模型参数构建之中, 以更准确评估和预测全球变化下森林生态系统土壤C源/汇功能变化。

关键词: 土壤有机碳, 土壤碳组分, 氮沉降, 根际土壤, 非根际土壤, 针叶林

Abstract:

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