Modeling of early stage litter decomposition in Mediterranean mixed forests: Functional aspects affected by local climate

Abstract: Litter decomposition is an important process occurring in forest ecosystems, where it affects the carbon balance as a whole. In Mediterranean area, seasonal changes and climate variations associated to latitude and structural characteristics of forest stands have a real effect on decomposition rates. Current leaf litter decomposition models are frequently too general to represent local climate variations in Mediterranean forests. We developed a new dynamic semi-empirical-based model, which simulated the early stage of decomposition of leaf litter based on local climate conditions and few operational parameters. Leaf litter was divided in two components, settled on different carbon compound concentrations. The effects of temperature and moisture were characterized by specific equations and the decomposition rates were time-depending functions. Equations were calibrated by the best fitting procedure performed on field data obtained by the litterbag method followed in mixed deciduous forests in central Apennines (Italy). Model validation showed an excellent correlation between observed and predicted values (R2 between 0.89 and 0.95), predicting thus differences in decomposition rates among different local climates. The simple structure of the model and the satisfactory reliability of outputs are important features for a practical alternative to other CO2 release evaluation methods applied to forest ecosystems.