Effects of the addition of forest floor extracts on soil carbon dioxide efflux Academic Article uri icon


  • Composition and effects of additions of fibric (Oi) and hemic/sapric (Oe + Oa) layer extracts collected from a 20-year-old stand of radiata pine (Pinus radiata) on soil carbon dioxide (CO2) evolution were investigated in a 94-day aerobic incubation. The 13C nuclear magnetic resonance spectroscopy indicated that Oi layer extract contained greater concentrations of alkyl C while Oe + Oa layer extract was rich in carboxyl C. Extracts from Oi and Oe + Oa layers were added to a forest soil at two different polyphenol concentrations (43 and 85 μg g-1 soil) along with tannic acid (TA) and glucose solutions to evaluate effects on soil CO2 efflux. CO2 evolution was greater in amended soils than control (deionized water) indicating that water-soluble organic carbon (WSOC) was readily available to microbial degradation. However, addition of WSOC extracted from both Oi and Oe + Oa layers containing 85 μg polyphenols g-1 soil severely inhibited microbial activity. Soils amended with extracts containing lower concentrations of polyphenols (43 μg polyphenols g-1 soil), TA solutions, and glucose solutions released 2 to 22 times more CO2-C than added WSOC, indicating a strong positive priming effect. The differences in CO2 evolution rates were attributed to chemical composition of the forest floor extracts. © 2006 Springer-Verlag.

author list (cited authors)

  • Ganjegunte, G. K., Condron, L. M., Clinton, P. W., Davis, M. R., & Mahieu, N.

citation count

  • 9

publication date

  • April 2006