Litter bag method was used in this study on the twig decomposition of an oak (Quercus liaotungensis Koidz.) which is dominant in the warm temperate deciduous forests. A consecutive five-year investigation was carried out to measure the changes of organic components in the twig litter. The decomposition of oak twigs based on rates of the mass loss during the first five years was simulated using the Olson exponential equation. The simulated data fit well with the observed values. Oak twigs were predicted to reach 95% decomposition within 21 years. During the first five yeats, the concentration of protein in the remaining litter increased from 3.5% to 5.5%, while the concentration of semicellulose decreased from 16.0% to 8.0%. However, there was no obvious change in the concentrations of lignin and cellulose. The loss of lignin, crude-cellulose, cellulose and semicellulose could be well simulated using the Olson exponential equation. However, this was not so effective for protein.
