植物生态学报 ›› 2021, Vol. 45 ›› Issue (5): 507-515.DOI: 10.17521/cjpe.2020.0231

所属专题: 青藏高原植物生态学:植物-土壤-微生物 土壤呼吸 碳储量

• 研究论文 • 上一篇    下一篇

若尔盖湿地高寒草甸退化过程中土壤有机碳含量变化及成因分析

董利军1, 李金花1,*(), 陈珊1, 张瑞1, 孙建2, 马妙君1   

  1. 1兰州大学生命科学学院, 草地农业生态系统国家重点实验室, 兰州 730000
    2中国科学院地理科学与资源研究所生态网络观测与模拟重点实验室, 北京 100101
  • 收稿日期:2020-07-13 接受日期:2020-10-23 出版日期:2021-05-20 发布日期:2020-12-09
  • 通讯作者: 李金花
  • 作者简介:*(jinhuali@lzu.edu.cn)
  • 基金资助:
    国家重点研发计划(2017YFC0504802)

Changes in soil organic carbon content and their causes during the degradation of alpine meadows in Zoigê Wetland

DONG Li-Jun1, LI Jin-Hua1,*(), CHEN Shan1, ZHANG Rui1, SUN Jian2, MA Miao-Jun1   

  1. 1State Key Laboratory of Grassland Agro-ecosystem, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
    2Key Laboratory of Ecosystem Network Observation and Modelling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
  • Received:2020-07-13 Accepted:2020-10-23 Online:2021-05-20 Published:2020-12-09
  • Contact: LI Jin-Hua

摘要:

土壤碳输入与输出之间的收支差决定土壤有机碳(SOC)含量。若尔盖湿地高寒草甸退化过程中, 土壤碳输入和输出哪个过程对SOC含量的影响占主导作用还不明确。该研究用空间序列代替时间序列的方法研究了若尔盖湿地高寒草甸不同退化阶段(高寒草甸(AM)、轻度退化高寒草甸(SD)和重度退化高寒草甸(HD)) SOC含量变化及原因。首先, 通过测定高寒草甸退化阶段上主要的土壤理化性状、微生物生物量、植物生物量和功能群组成的变化, 分析了退化阶段上土壤碳输入量的变化及原因; 其次, 结合室内土壤碳矿化培养实验结果和研究区的月平均气温以及土壤呼吸温度敏感性(Q10)估算了该区域土壤碳输出, 并分析了其变化原因; 最后, 分析了造成SOC含量变化的主要原因和过程。结果表明: 在退化梯度上, 土壤含水量(SWC)、SOC和全氮(TN)含量、微生物生物量碳氮含量降低; 植物群落组成逐渐从莎草科、禾本科占优势过渡到杂类草占优势, 且植物生物量降低; SOC矿化量降低; 有机碳潜在积累量降低(与AM阶段相比, SD和HD阶段有机碳潜在输入量、输出量和积累量分别降低了16%、18%、15%和59%、63%、41%)。SWC降低引起土壤容重、SOC含量、TN含量、全磷含量、C:N的改变, 进而导致植物功能群分布模式和土壤微生物的变化, 最终引起SOC输入和输出量的降低。SWC降低导致的植物碳潜在输入量的降低是若尔盖湿地高寒草甸退化过程中SOC含量下降的主要原因。

关键词: 高寒草甸, 土壤有机碳, 碳输入, 土壤累积碳矿化

Abstract:

Aims The balance between soil organic carbon (SOC) input and output processes determines SOC content. However, it is not clear which of the two processes dominantly affect SOC content during the degradation of alpine meadows in Zoigê Wetland. In this study, the changes in SOC contents of alpine meadows and their causes at different degradation stages (alpine meadow (AM), slightly degraded alpine meadow (SD), and heavily degraded alpine meadow (HD)) in the Zoigê Wetland were investigated using the method of spatial sequence instead of temporal successional sequence.
Methods First, the changes in C input to soil and their causes along the degradation gradient were analyzed by investigating main soil physicochemical properties, microbial biomass, plant biomass and community composition of plant functional groups at different degradation stages. Secondly, the changes in the C output from soil were estimated based on lab incubation experiments of soil C mineralization and the temperature sensitivity of soil respiration (Q10) and monthly average air temperature of the Zoigê Wetland. Finally, the main causes and processes leading to changes in SOC content along the degradation gradient were analyzed.
Important findings The results showed that soil water content (SWC), SOC content, total nitrogen (TN) content, microbial biomass C and N content decreased with the increase of degradation. Plant community composition gradually changed from sedges and grasses dominated community to forbs dominated community. Plant biomass and SOC mineralization rate decreased during the degradation of alpine meadows. The potential accumulation of organic C reduced during the degradation (compared with AM, the potential input, output and accumulation of organic C in SD and HD decreased by 16%, 18%, 15% and 59%, 63%, 41%, respectively). The decrease in SWC changed soil physical and chemical properties, including bulk density, SOC content, TN content, total phosphorus content, and C:N, which led to the shifts in the distribution pattern of plant functional groups and in soil microorganisms, consequently reducing the inputs and outputs of SOC. The decrease in potential plant-derived C input to soil caused by decreased SWC was the main reason for the decline in SOC content along the degradation gradient of alpine meadows in Zoigê Wetland.

Key words: alpine meadow, soil organic carbon, carbon input, soil accumulative carbon mineralization