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Effects of biological soil crust at different succession stages in hilly region of Loess Plateau on soil CO2 flux.

WANG Ai-guo1,2, ZHAO Yun-ge2, XU Ming-xiang1,2, YANG Li-na2,3, MING Jiao2,3   

  1. (1College of Forestry, Northwest A&F University, Yangling 712100, Shaanxi, China; 2State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University, Yangling 712100, Shaanxi, China; 3Graduate University of Chinese Academy of Sciences, Beijing 100049, China)
  • Online:2013-03-18 Published:2013-03-18

Abstract: Biological soil crust (biocrust) is a compact complex layer of soil, which has photosynthetic activity and is one of the factors affecting the CO2 flux of soilatmosphere interface. In this paper, the soil CO2 flux under the effects of biocrust at different succession stages on the re-vegetated grassland in the hilly region of Loess Plateau was measured by a modified LI-8100 automated CO2 flux system. Under light condition, the soil CO2 flux under effects of cyanobacteria crust and moss crust was significantly decreased by 92% and 305%, respectively, as compared with the flux without the effects of the biocrusts. The decrement of the soil CO2 flux by the biocrusts was related to the biocrusts components and their biomass. Under the effects of dark colored cyanobacteria crust and moss crust, the soil CO2 flux was decreased by 141% and 484%, respectively, as compared with that in bare land. The diurnal curve of soil CO2 flux under effects of biocrusts presented a trend of ‘droprisedrop’, with the maximum carbon uptake under effects of cyanobacteria crust and moss crust being 0.13and -1.02 μmol CO2·m-2·s-1 and occurred at about 8:00 and 9:00 am, respectively, while that in bare land was unimodal. In a day (24 h), the total CO2 flux under effects of cyanobacteria crust was increased by 7.7%, while that under effects of moss crust was decreased by 29.6%, as compared with the total CO2 flux in bare land. This study suggested that in the hilly region of Loess Plateau, biocrust had significant effects on soil CO2 flux, which should be taken into consideration when assessing the carbon budget of the ‘Grain for Green’ eco-project.