Experimental determination of the degradation rate for some forest residue fuel components at different temperatures and oxygen concentrations.
Ernstson M.L. | Jirjis R. | Rasmuson A.
The microbial degradation of forest fuel materials of Norway spruce, including needles, outer bark and sapwood, is studied under controlled laboratory conditions. In the experiments the temperature is varied between 15-55 deg C and the oxygen concentration between 1-21 vol%. The experiments were run for up to 59 days. The influence of higher carbon dioxide gas concentration and initial sterilization of the material were also studied. The experiments show quantitatively the functional relations between the degradation rates for the different materials and the oxygen concentration and the temperature. The reaction rate is highest for needles, then bark and last sapwood. Maximal rates of 0.4 and 0.2 and 0.05 kg/kg DM/month are obtained, respectively. A, more or less, linear dependence between degradation rate and oxygen concentration is obtained. The temperature dependence shows an optimum in the range between 25 and 40 deg C. At 15 deg C the reaction rate is low and at 55 deg C it is negligible. Attempts were made to correlate the degradation rate with the fungal acativity. For that purpose, the germinating and the total number of spores were counted. However, no simple correlation was found between degradation rate and number of spores.Show more [+] Less [-]