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Relations between Carbon Dioxide Fluxes and Environmental Factors of Kobresia humilis Meadows and Potentilla fruticosa Meadows |
| ZHAO Liang1, XU Shixiao1, ZHAO Xinquan1, GU Song1, LI Yingnian2, TANG Yanhong3, DU Mingyuan4, YU Guirui5 |
| 1.Northwest Plateau Institute of Biology, Chinese Academy of Science, Xining 810001, China; Key Laboratory of Adaption and Evolution of Peatean Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xin′ging 810001, China; 2.Northwest Plateau Institute of Biology, Chinese Academy of Science, Xining 810001, China; 3.National Institute for Environmental Studies, Tsukuba, Ibaraki 3050053, Japan; 4.National Institute for Agro-Environmental Science, Tsukuba, Ibaraki 3058604, Japan; 5.Institute of Geographic Sciences and Natural Resources Research, Beijing 100101, China |
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Abstract Carbon dioxide fluxes of Kobresia humilis and Potentilla fruticosa shrub meadows, two typical ecosystems in the Qinghai-Tibet Plateau, were measured by eddy covariance technology and the data collected in August 2003 were employed to analyze the relations between carbon dioxide fluxes and environmental factors of the ecosystems. August is the time when the two ecosystems reach their peak leaf area indexes and stay stable, and also the period when the net carbon absorptions of Kobresia humilis and Potentilla fruticosa shrub meadows reach 56.2 g C · m-2 and 32.6 g C · m-2, with their highest daily carbon dioxide absorptions standing at 12.7 ?mol · m-2 · s-1 and 9.3 ?mol · m-2 · s-1, and their highest carbon discharges at 5.1 ?mol · m-2 · s-1 and 5.7 ?mol · m-2 · s-1, respectively. At the same photosynthetic photo flux densities (PPFD), the carbon dioxide-uptake rate of the Kobresia humilis meadow is higher than that of the Potentilla fruticosa shrub meadow; where the PPFD are highe r than 1,200 μmol · m-2 · s-1. The carbon dioxide uptake rates of the two ecosystems declined as air temperature increased, but the carbon dioxide uptake rate of the Kobresia humilis meadow decreased more quickly (–0.086) than that of the Potentilla fruticosa shrub meadow (–0.016). Soil moistures exert influence on the soil respirations and this varies with the vegetation type. The daily carbon dioxide absorptions of the ecosystems increase with increased diurnal temperature differences and higher diurnal temperature differences result in higher carbon dioxide exchanges. There exists a negative correlation between the vegetation albedos and the carbon dioxide fluxes.
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Issue Date: 05 September 2007
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