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Biogeosciences An interactive open-access journal of the European Geosciences Union
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Volume 7, issue 1 | Copyright

Special issue: CarboEastAsia

Biogeosciences, 7, 395-407, 2010
https://doi.org/10.5194/bg-7-395-2010
© Author(s) 2010. This work is distributed under
the Creative Commons Attribution 3.0 License.

  29 Jan 2010

29 Jan 2010

Effects of multiple environmental factors on CO2 emission and CH4 uptake from old-growth forest soils

H. J. Fang1, G. R. Yu1, S. L. Cheng2, T. H. Zhu2, Y. S. Wang3, J. H. Yan4, M. Wang5, M. Cao6, and M. Zhou7 H. J. Fang et al.
  • 1Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
  • 2Graduate University of Chinese Academy of Sciences, Beijing 100049, China
  • 3Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
  • 4South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China
  • 5Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China
  • 6Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China
  • 7College of Ecology and Environmental Sciences, Inner Mongolia Agricultural University, Hohhot 010019, China

Abstract. To assess contribution of multiple environmental factors to carbon exchanges between the atmosphere and forest soils, four old-growth forests referred to as boreal coniferous forest, temperate needle-broadleaved mixed forest, subtropical evergreen broadleaved forest and tropical monsoon rain forest were selected along eastern China. In each old-growth forest, soil CO2 and CH4 fluxes were measured from 2003 to 2005 applying the static opaque chamber and gas chromatography technique. Soil temperature and moisture at the 10 cm depth were simultaneously measured with the greenhouse gas measurements. Inorganic N (NH4+-N and NO3-N) in the 0–10 cm was determined monthly. From north to south, annual mean CO2 emission ranged from 18.09 ± 0.22 to 35.40 ± 2.24 Mg CO2 ha−1 yr−1 and annual mean CH4 uptake ranged from 0.04 ± 0.11 to 5.15 ± 0.96 kg CH4 ha−1 yr−1 in the four old-growth forests. Soil CO2 flux in the old-growth forests was mainly driven by soil temperature, followed by soil moisture and NO3-N. Temperature sensitivity (Q10) of soil CO2 flux was lower at lower latitudes with high temperature and more precipitation, probably because of less soil organic carbon (SOC). Soil NO3 accumulation caused by environmental change was often accompanied by an increase in soil CO2 emission. In addition, soil CH4 uptake decreased with an increase in soil moisture. The response of soil CH4 flux to temperature was dependent upon the optimal value of soil temperature in each forest. Soil NH4+-N consumption tended to promote soil CH4 uptake in the old-growth forests, whereas soil NO3-N accumulation was not conducive to CH4 oxidation in anaerobic condition. These results indicate that soil mineral N dynamics largely affects the soil gas fluxes of CO2 and CH4 in the old-growth forests, along with climate conditions.

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