Chin J Plan Ecolo ›› 2010, Vol. 34 ›› Issue (7): 770-780.DOI: 10.3773/j.issn.1005-264x.2010.07.002

• Research Articles • Previous Articles     Next Articles

Variation in net CO2 exchange, gross primary production and its affecting factors in the planted pasture ecosystem in Sanjiangyuan Region of the Qinghai-Tibetan Plateau of China

WU Li-Bo1,2; GU Song3,1*; ZHAO Liang1; XU Shi-Xiao1; ZHOU Hua-Kun1; FENG Chao1,2; Xu Wei-Xin1,2; LI Ying-Nian1; ZHAO Xin-Quan1; and TANG Yan-Hong4   

  1. 1Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008, China;
    2Graduate University of Chinese Academy of Sciences, Beijing 100049, China;
    3College of Life Sciences, Nankai University, Tianjin 300071, China;
    4National Institute for Environmental Studies, Tsukuba, Ibaraki, 305-8506,Japan
  • Received:2009-01-15 Revised:2009-04-02 Online:2010-07-01 Published:2010-07-01
  • Contact: GU Song

Abstract: Aims Our objective was to understand seasonal and diurnal variations in CO2 exchange of a grassland ecosystem by clarifying the carbon cycle and its affecting factors for a planted pasture ecosystem in the Sanjiangyuan Region of the Qinghai-Tibetan Plateau.
Methods We used the eddy covariance method to measure net ecosystem CO2 exchange (NEE) and environmental factors in the planted pasture (Elymus nutans) ecosystem in 2006.
Important findings Daily maximum uptake and release of CO2 were 6.56 and –4.87 g CO2·m–2·d–1, respectively. Maximum rates of NEE uptake and release were –0.35 and 0.22 mg CO2·m–2·s–1, respectively. Annual gross primary production (GPP) was 1 761 g CO2·m–2·a–1, of which more than 90% was consumed by ecosystem respiration (Reco). Annual NEE was –111 g CO2·m–2. In the growing season, maximum and minimum Reco/GPP values
were 90% in May and 79% in June, respectively. The Q10 was 4.81, which is higher than in other ecosystems. The NEE was mostly influenced by photosynthetic photon flux density (PPFD), temperature and vapor pressure deficit (VPD). The Reco was mainly affected by soil temperature at 5 cm depth (Ts).