Chin J Plant Ecol ›› 2018, Vol. 42 ›› Issue (3): 397-405.DOI: 10.17521/cjpe.2015.0395

• Research Articles • Previous Articles    

Responses of ecosystem carbon exchange to multi-level water addition in an alpine meadow in Namtso of Qinghai-Xizang Plateau, China

GENG Xiao-Dong1,2,Xu Ri1,3,*(),LIU Yong-Wen1,3   

  1. 1 Key Laboratory of Alpine Ecology and Biodiversity, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China
    2 University of Chinese Academy of Sciences, Beijing 100049, China
    3 Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing 100101, China
  • Online:2018-03-20 Published:2017-06-16
  • Contact: Ri Xu
  • Supported by:
    Supported by the National Natural Science Foundation of China(41175128);Supported by the National Natural Science Foundation of China(41575152);the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA05020402);the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA05050404-3-2)

Abstract:

Aims Alpine meadow is widely distributed in the Qinghai-Xizang Plateau, playing an important role in regulating the regional carbon budget. Over the Qinghai-Xizang Plateau, precipitation generally shows an increasing trend during past the several decades, and is projected to increase during the 21st century. Alpine meadow is very susceptible to such climate change, but it remains unclear how its ecosystem carbon exchange responses to precipitation change. In this study, we aim to clarify the effects of altered precipitation on ecosystem carbon exchange in the alpine meadow by conducting a manipulative field experiment.

Methods We conducted a precipitation manipulation experiment at an alpine meadow site in the Namtso area of central Qinghai-Xizang Plateau during 2013 to 2014. A total of six treatments were established, with levels of water addition set for 0%, 20%, 40%, 60%, 80% and 100%, respectively, of equivalent increases in precipitation. We investigated the effects of water addition on gross ecosystem production (GEP), ecosystem respiration (ER), net ecosystem carbon exchange (NEE), and environmental conditions during the growing season.

Important findings The increasing water addition substantially increased soil moisture, but had no significant effect on soil temperature. Both GEP and NEE significantly increased with water addition equivalent to 20% of increases in precipitation, but were suppressed with further increases in the level of water addition. No significant difference was detected in ER across the water addition treatments. Our study suggests that: 1) The change in soil moisture significantly affected NEE and GEP but had a weak effect on ER in the alpine meadow; 2) CO2 sequestration in the alpine meadow could be stimulated by moderate increases (e.g. 20%-40%) in precipitation.

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Key words: carbon exchange, water addition, alpine meadow, Qinghai-Xizang Plateau