Organic Matter DYnamic model (OMDY) predicts the wood debris decomposition of ten Mediterranean species

Backgrounds and Aims: Forest litter is mainly composed by leaves, roots and wood debris (WD) residues. WD decomposition in Mediterranean ecosystems has received less attention compared to other materials and to boreal, tropical and temperate biomes. The OMDY model describes organic matter decomposition using 13C NMR spectroscopy. Methods: The mass loss and the 13C NMR of ten mediterranean wood and shrub species were monitored for a long-term (5 years) experiment. The regularized generalized regression LASSO was used to select the NMR spectra regions more predictable for the WD decomposition. The OMDY model was applied to simulate the long-term decomposition experiment of ten mediterranean wood and shrub species. Results: WD species, chemical composition and decomposition time significantly influenced the dynamics of the remaining mass during the decomposition. The NMR analysis revealed an increase in alkyl C and carbonyl C while a decrease in di-O-alkyl C and O-alkyl C. Pistacia lentiscus L. showed the highest decomposition, with a O-alkyl C declining and alkyl C rising. Erica arborea L. decomposed less, showing smaller decreases in O-alkyl C, lower alkyl C accumulation. The LASSO method identified three chemical regions as crucial for WD decomposition. The OMDY model, using as input these NMR molecular regions, demonstrated a high capacity to describe long-term WD decomposition. Conclusions: The model is adaptable to describe the decomposition of wood. The results show that the model is general, as NMR can describe different materials' spectra and ordinary differential equations predict their reduction.