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Responses of CO2 flux in a saline desert of Northwest China to two contrasting extreme precipitation years.

LIU Ran, LI Yan**, LIU Yan   

  1. (State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China)
  • Online:2013-10-10 Published:2013-10-10

Abstract: Eddy covariance technique was used to measure carbon flux in a desert halophyte community in Fukang of Xinjiang during two hydrological years (2006 and 2007) with contrasting precipitation. The first hydrological year was dry (2006), with the total annual precipitation of 129 mm and the second was wet (2007), with the total annual precipitation of 231 mm. The main objective of this study was to characterize the seasonal and annual carbon flux of a desert halophyte community using the eddy covariance technique to determine the sensitivity of the system to the varying amounts of precipitation. The results showed that the daily carbon absorption rate of the ecosystem was obviously lower in 2006 than in 2007, with the maximum value being -0.4 g C·m-2·d-1 and -1.6 g C·m-2·d-1, respectively. The duration of the growth season was 120 days in 2006, and 160 days in 2007. The carbon absorption, gross ecosystem production (GEP), and ecosystem respiration (Reco) were -5 g C·m-2·a-1, 114.9 g C·m-2·a-1 and 110.1 g C·m-2·a-1  in 2006, and -40 g C·m-2·a-1, 257.7 g C·m-2·a-1 and 218.2 g C·m-2·a-1 in 2007, respectively. The linear relationship between the GEP and ecosystem evapotranspiration was obviously weaker in 2006 than in 2007, with the coefficient of determination being 0.40 and 0.71, respectively. The vegetation community survey revealed that the proportion of annual herbaceous plants in 2007 increased, which could fully utilize precipitation to improve the ecosystem productivity.