植物生态学报 ›› 2019, Vol. 43 ›› Issue (7): 576-584.DOI: 10.17521/cjpe.2019.0009

• 研究论文 • 上一篇    下一篇

13C脉冲标记揭示放牧对高寒草甸同化碳分配的影响

陈锦1,2,宋明华1,*(),李以康3   

  1. 1中国科学院地理科学与资源研究所生态系统网络观测与模拟重点实验室, 北京 100101
    2中国科学院大学, 北京 100049
    3中国科学院西北高原生物研究所, 西宁 810008
  • 收稿日期:2019-01-10 接受日期:2019-06-25 出版日期:2019-07-20 发布日期:2019-12-12
  • 通讯作者: 宋明华
  • 基金资助:
    国家重点研发计划(2016YFC0502001);国家重点研发计划(2016YFC0501803);国家自然科学基金(41671263)

13C pulse labeling reveals the effects of grazing on partitioning of assimilated carbon in an alpine meadow

CHEN Jin1,2,SONG Ming-Hua1,*(),LI Yi-Kang3   

  1. 1Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
    2University of Chinese Academy of Sciences, Beijing 100049, China
    3Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008, China
  • Received:2019-01-10 Accepted:2019-06-25 Online:2019-07-20 Published:2019-12-12
  • Contact: SONG Ming-Hua
  • Supported by:
    Supported by the National Key R&D Program of China(2016YFC0502001);Supported by the National Key R&D Program of China(2016YFC0501803);the National Natural Science Foundation of China(41671263)

摘要:

放牧是人类对草地进行利用的重要方式之一, 放牧影响草地生态系统的结构和功能, 改变植物光合碳(C)分配, 进而改变土壤有机碳的储存。青藏高原的高寒草甸是世界上海拔最高的草地生态系统, 寒冷季节长等独特的环境特点使其具有高的土壤有机碳含量。为了揭示长期轻度放牧对植物光合碳分配及植物光合碳在各库之间运移的影响, 基于在青藏高原矮嵩草草甸开展的长期冬季轻度放牧和围栏封育实验, 利用 13C示踪方法揭示了放牧对光合碳在植物地上、地下组织的分配以及光合碳在植物、土壤各碳库中的运移和滞留。研究结果发现, 在 13C标记之后第30天, 冬季轻度放牧样地的植物地上部分内 13C约占开始时 13C含量的32%, 根和土壤中的 13C约占22%, 植物地上部分呼吸中的 13C量约占30%。在放牧和围封这两个不同处理中, 土壤中光合碳的滞留以及光合碳随土壤呼吸释放的速率存在显著差异。长期冬季轻度放牧促使植物将更多的光合碳输入到根和土壤碳库中。与围栏封育处理相比较, 放牧处理下的 13C从植物地上部分输入到地下的速率较快, 通过土壤呼吸释放的速率也快, 而植物地上部分和植物地上部分呼吸中 13C的量较低。另外, 高寒矮嵩草草甸土壤C储量在冬季轻度放牧和围栏封育处理下没有显著差异。我们的研究表明, 尽管冬季轻度放牧改变了植物光合碳分配在地上和地下碳库中的分配, 但是没有显著影响土壤碳库储量。

关键词: 放牧, 13C同位素标记, 高寒草甸, 光合碳分配

Abstract:

Aims In this study, we aim to understand how grazing would influence the partitioning of assimilated carbon in an alpine meadow on the Qinghai-Xizang Plateau.
Methods Measurements on carbon partitioning were made in a long-term grazing experiment consisting of light winter grazing and enclosure treatments. The 13C tracer method was used to determine the partitioning and transportation of assimilated carbon into different carbon pools.
Important findings On the 30th day following the labeling, shoots retained 32% of the initial 13C, and roots and soil together retained 22%; about 30% of the initial 13C were lost through shoot respiration. There were significant differences in the retention in soil, and the respiratory emission from soil, of assimilated carbon between the light grazing and enclosure treatments. Under light grazing, plants invested more assimilated carbon into the root and soil carbon pools. The rate of 13C transportation from shoots to soil and the rate of respiratory 13C release from soil were both greater, and the retention of 13C in and respiratory release from shoots were lower, under light grazing than under enclosure. Our results suggest that grazing is an important mechanism for maintenance of grassland. Grazing may cause changes in the structure and functioning of ecosystems, and induce large variations in soil carbon storage. Alpine meadow in the Qinghai-Xizang Plateau is amongst the grasslands with highest elevation in the world, and has large soil carbon storage due to low temperatures. We found no difference in soil C stocks between light grazing and enclosure treatments, indicating that light grazing would have no significant impact on soil carbon stocks.

Key words: grazing, 13C isotope labeling, alpine meadow, partitioning of assimilated carbon