Effects of the addition of forest floor extracts on soil carbon dioxide efflux
Academic Article
Overview
Research
Identity
Additional Document Info
Other
View All
Overview
abstract
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 g 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 g polyphenols g-1 soil severely inhibited microbial activity. Soils amended with extracts containing lower concentrations of polyphenols (43 g 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.
