Inter- and Intra-Specific Variation in Anatomical and Morphological Shapes and Biochemical Ratios of Sun, Intermediate and Shade Leaves from Three Deciduous Tree Species

Previously we revealed significant differences in biochemical composition of sun and shade leaf litters from chestnut, oak and beech tree species that were related to mass losses. Total lignin of the leaf litters was the dominant variable affecting their decomposition rates. Proximate analysis measured an aggregation of recalcitrant compounds mostly affected microbial activity, rather than a specific biochemical constituent. It was also noted that differences in the decomposition rates of sun and shade leaves within species showed the same anomalous patterns of decomposition described by other researchers, whereby species with rapid initial mass losses had larger residual litter masses than species decomposing slowly at constant rates. We were unable to explain this phenomenon in terms of litter chemistry and suggested that this was an artefact caused by changes in the fungal community within the forest floor material used as an inoculum bed over the 2-year incubation period. In the previous study, we did not consider in detail the inter- and intra-specific variation in anatomical and morphological shapes and biochemical ratios of TFA-carbohydrates (mainly sugar constituents of hemicellulose) and phenylpropanoid derivatives (PPDs) of lignin in sun, intermediate and shade leaves which are taken as an index of lignin depolymerisation by white-rot fungi and also used to assign the proportions of plant- and microbial-derived carbohydrates by several investigators. Here, we revealed and discussed the effects of variation in anatomical and morphological shapes and biochemical ratios on litter decomposition rates. Those results can be used in future studies in order to explain the unknown phenomenon why decomposition rates subsequently decrease in the leaf litters, which initially decompose at higher rates?