Litter decomposition in Mediterranean ecosystems: Modelling the controlling role of climatic conditions and litter quality

• Published in: Applied soil ecology : a section of Agriculture, ecosystems & environment ecosystems & environment, 2011-09, Vol.49, p.148-157
• Main Authors: Incerti, Guido, Bonanomi, Giuliano, Giannino, Francesco, Rutigliano, Flora Angela, Piermatteo, Daniela, Castaldi, Simona, De Marco, Anna, Fierro, Angelo, Fioretto, Antonietta, Maggi, Oriana, Papa, Stefania, Persiani, Anna Maria, Feoli, Enrico, De Santo, Amalia Virzo, Mazzoleni, Stefano
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; C model; C/N ratio; carbon; Chemical, physicochemical, biochemical and biological properties; drought; ecosystems; field experimentation; Fundamental and applied biological sciences. Psychology; Initial C pools; leaves; microbial communities; nitrogen content; Organic matter; Phillyrea; Physics, chemistry, biochemistry and biology of agricultural and forest soils; plant litter; Process-based model; Semi-arid ecosystems; simulation models; Soil science; soil texture; stand structure; summer; System dynamics; water temperature
• ISSN: 0929-1393; 1873-0272
• DOI: 10.1016/j.apsoil.2011.06.004

► A new litter decay model is presented with improved climate limiting effects. ► Litter quality is assessed without traditional N-based indices. ► Model was calibrated by controlled experiments and validated with field data. ► Litter decay simulation for 7 species in 3 Mediterranean sites was highly predictive. ► Decomposition in Mediterranean region is mostly dependent on water conditions. A new process-based model of litter decomposition, characterized by detailed climatic data input and simple litter quality parameters, is proposed. Compared to existing litter carbon models, specific implementations for temperature and moisture limiting effects have been adopted. The model is capable to represent decomposition processes in Mediterranean ecosystems, with summer drought slowing down, even at optimal temperatures, the litter decay rates of sclerophyll plants whose leaf masses are rich in structural compounds and low in N content. The model was calibrated by a best fitting procedure of two different datasets. First, unpublished results of litterbag experiments on leaf litter of 9 Mediterranean species, decomposing under controlled and not limiting temperature and water conditions, have been used to estimate the decay rate dependency from litter quality that was defined by only three initial C pools (labile, stable and recalcitrant compounds) instead of traditional N-based indices. Second, a set of published data from three medium-term field experiments on a single species, Phillyrea angustifolia, decomposing under different climatic conditions, have been used to estimate the limiting effects of temperature and moisture. The model was then validated against published data on seven other species and showed a correct reproduction of the major patterns of litter mass loss during decomposition processes of other seven different Mediterranean species. The model simulations, satisfactory for different litter types under a wide range of climatic conditions, suggest that factors which were not taken into account, such as initial litter N contents, microclimatic variations related to stand structure, soil chemistry and texture, and microbial communities, are not very significant for assessing decomposition dynamics in Mediterranean ecosystems. The minimal requirements of input data, the simple structure, and the easiness of parameterisation make our model, among the many other available litter carbon models, an attractive alternative for different research purposes,