Chin J Plant Ecol ›› 2010, Vol. 34 ›› Issue (3): 263-270.DOI: 10.3773/j.issn.1005-264x.2010.03.003

Special Issue: 青藏高原植物生态学:种群生态学

• Research Articles • Previous Articles     Next Articles

Short-term gas exchange responses of Betula utilis to simulated global warming in a timberline ecotone, eastern Tibetan Plateau, China

XU Zhen-Feng1,2, HU Ting-Xing1,*(), ZHANG Li1, ZHANG Yuan-Bin2, XIAN Jun-Ren1, WANG Kai-Yun3   

  1. 1Faculty of Forestry, Sichuan Agricultural University, Ya’an, Sichuan 625014, China
    2Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China
    3Shanghai Key Laboratory of Urbanization and Ecological Restoration, East China Normal University, Shanghai 200062, China
  • Received:2009-03-02 Accepted:2009-04-23 Online:2010-03-02 Published:2010-03-01
  • Contact: HU Ting-Xing


Aims Betula utilis is an important plant in the timberline ecotone of subalpine regions, Western Sichuan China. Our objective is to determine how this species changes its photosynthetic parameters under warming conditions.

Methods We studied the responses of gas exchange to simulated global warming using the open-top chamber (OTC) method. During the 2007 growing season, microclimate data between the OTC and the control (CK) were taken at 15-min intervals with an automatic recording system. In mid-August, the gas exchange of B. utilis seedlings in the OTC and the CK was measured with the LI-6400 Portable Photosynthesis System and a 6-cm2 leaf chamber. Comparisons between the OTCs and the control plots were analyzed by the Wilcoxon’s signed ranks test.

Important findings Warming significantly increased instantaneous leaf net photosynthetic rate (Pn), conductance (Gs) and transpiration (Tr) by 17.4%, 21.4% and 33.9%, respectively, and reduced leaf N concentration by 12.4%. Warming also enhanced the maximum net photosynthetic rate (Pnmax) (+19.6%), dark respiration rate (Rd) (+14.3%) and apparent quantum yield (AQY) (+7.9%), but did not influence the light compensation point (LCP) or the light saturation point (LSP) of B. utilis seedlings. Moreover, warming markedly increased the maximum rate of RuBP carboxylation (Vcmax) and rate of photosynthetic election transport (J), but there were no clear differences between treatments for triose phosphate use (TPU) and compensation CO2 (CCP). Our results indicated that in situ experimental warming had positive effects on the gas exchange of B. utilis seedlings. These responses could be helpful for the timberline species to adapt to future global warming.

Key words: Betula utilis, ecotone in timberline, open-top chamber, Pn -Ci curve, Pn -PAR curve