Get access

Interannual variability in global soil respiration, 1980–94

Authors

  • James W. Raich,

    Corresponding author
    1. Department of Botany, Iowa State University, Ames, IA, 50011, USA;
      James W. Raich, Department of Botany, 353 Bessey Hall, Iowa State University, Ames, IA, 50011-1020, USA. fax + 5152941337, e-mail: jraich@iastate.edu
    Search for more papers by this author
  • Christopher S. Potter,

    1. Ecosystem Science and Technology Branch, NASA-Ames Research Center, Moffett Field, CA 94035, USA;
    Search for more papers by this author
  • Dwipen Bhagawati

    1. Department of Civil and Construction Engineering, Iowa State University, Ames, IA, 50011 USA
    Search for more papers by this author
    • 1

      Present address: Epic Systems Corporation, 5301 Tokay Boulevard, Madison, WI, 53711, USA


James W. Raich, Department of Botany, 353 Bessey Hall, Iowa State University, Ames, IA, 50011-1020, USA. fax + 5152941337, e-mail: jraich@iastate.edu

Abstract

We used a climate-driven regression model to develop spatially resolved estimates of soil-CO2 emissions from the terrestrial land surface for each month from January 1980 to December 1994, to evaluate the effects of interannual variations in climate on global soil-to-atmosphere CO2 fluxes. The mean annual global soil-CO2 flux over this 15-y period was estimated to be 80.4 (range 79.3–81.8) Pg C. Monthly variations in global soil-CO2 emissions followed closely the mean temperature cycle of the Northern Hemisphere. Globally, soil-CO2 emissions reached their minima in February and peaked in July and August. Tropical and subtropical evergreen broad-leaved forests contributed more soil-derived CO2 to the atmosphere than did any other vegetation type (∼30% of the total) and exhibited a biannual cycle in their emissions. Soil-CO2 emissions in other biomes exhibited a single annual cycle that paralleled the seasonal temperature cycle. Interannual variability in estimated global soil-CO2 production is substantially less than is variability in net carbon uptake by plants (i.e., net primary productivity). Thus, soils appear to buffer atmospheric CO2 concentrations against far more dramatic seasonal and interannual differences in plant growth. Within seasonally dry biomes (savannas, bushlands and deserts), interannual variability in soil-CO2 emissions correlated significantly with interannual differences in precipitation. At the global scale, however, annual soil-CO2 fluxes correlated with mean annual temperature, with a slope of 3.3 Pg C y−1 per °C. Although the distribution of precipitation influences seasonal and spatial patterns of soil-CO2 emissions, global warming is likely to stimulate CO2 emissions from soils.

Get access to the full text of this article

Ancillary