DYNAMICS OF CARBON POOLS IN A SOIL COVERED WITH DIFFERENT FOREST TREE SPECIES AFTER CONTROLLED HEATING AND WETTING

Fire-induced soil heating deeply affects soil organic C pools and their dynamics. The objective of this study was to investigate, in a soil covered with different forest tree species (Eucalyptus camaldulensis, E. occidentalis, Pinus halepensis, and Cupressus sempervirens), the effect of controlled heating on C pools and C mineralization dynamics. Soil samples were heated under controlled condition in laboratory (160 and 380°C) and then wetted with distilled or sea water to simulate the extinction of wildfires. Soil organic C pools react to heating in different way depending on forest tree species. Total organic C was almost halved following the heating of soils at 380°C. Soil covered with Pinus halepensis showed the greater decrease in organic C. Heating increased the amount of the labile C pool, promoted a direct emission of CO2 from soil during the combustion phase and an indirect emission by increasing the substrates readily available for microbial respiration. Sea water applied after heating has generally reduced CO2 emission.