Seasonal variations in organic materials and calorific values of Japanese cedar and cypress leaves

We investigated the seasonal variations of organic materials and calorific values of the leaves of the Japanese cedar (Cryptomeria japonica) and the Japanese cypress (Chamaecyparis obtusa). While in April and May, the yields of alcohol–benzene extracts and Klason lignin of cedar and cypress leaves decreased; the yields of hemicellulose increased significantly compared with the annual average. The calorific values decreased simultaneously with the yields of alcohol–benzene extracts and Klason lignins of both types of leaves. The alcohol–benzene extracts yielded the highest calorific values (Japanese cedar, 33.4 ± 0.04 MJ/kg and Japanese cypress, 32.8 ± 0.37 MJ/kg), and hemicelluloses yielded the lowest calorific values of organic components (Japanese cedar, 12.8 ± 0.22 MJ/kg and Japanese cypress, 14.5 ± 1.02 MJ/kg). These results indicate that the changes of calorific values of these leaves are due to the changes of organic materials through the year.