loading page

Permafrost Degradation Diminishes Terrestrial Ecosystem Carbon Sequestration Capacity on the Qinghai-Tibetan Plateau
  • +3
  • Lei Liu,
  • Qianlai Zhuang,
  • Dongsheng Zhao,
  • Du Zheng,
  • Dan Kou,
  • Yuanhe Yang
Lei Liu
Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences
Author Profile
Qianlai Zhuang
Purdue University
Author Profile
Dongsheng Zhao
Key laboratory of land surface pattern and simulation, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences

Corresponding Author:[email protected]

Author Profile
Du Zheng
Institute of Geographical Sciences and Natural Resources Research, CAS
Author Profile
Dan Kou
Biogeochemistry Research Group, Department of Environmental and Biological Sciences, University of Eastern Finland
Author Profile
Yuanhe Yang
Institute of Botany, CAS
Author Profile

Abstract

Effects of permafrost degradation on carbon (C) and nitrogen (N) cycling on the Qinghai-Tibetan Plateau (QTP) have rarely been analyzed. This study used a revised process-based biogeochemical model to quantify the effects in the region during the 21st century. We found that permafrost degradation would expose 0.98±0.49 (mean±SD) and 2.17±0.38 Pg C of soil organic carbon under the representative concentration pathway (RCP) 4.5 and the RCP 8.5, respectively. Among them about 60% will be decomposed, enhancing heterotrophic respiration by 9.54±5.20 (RCP 4.5) and 38.72±17.49 (RCP 8.5) Tg C/yr in 2099. Deep soil N supply due to thawing permafrost is not accessible to plants, providing limited benefits to plant growth and only stimulating net primary production by 6.95±5.28 (RCP 4.5) and 27.97±12.82 (RCP 8.5) Tg C/yr in 2099. As a result, permafrost degradation would weaken the regional C sink (net ecosystem production) by 303.55±254.80 (RCP 4.5) and 518.43±234.04 (RCP 8.5) Tg C cumulatively during 2020–2099. Permafrost degradation has a higher influence on C balance of alpine meadow than alpine steppe ecosystems on the QTP. The shallower active layer, higher soil C and N stocks, and wetter environment in alpine meadow are responsible for its stronger response of C balance to permafrost thaw. This study highlights that permafrost degradation could continue to release large amounts of C to the atmosphere irrespective of potentially more nitrogen available from deep soils.
Feb 2022Published in Global Biogeochemical Cycles volume 36 issue 2. 10.1029/2021GB007068