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Abstract

Distinct O1 and O2 layers, representing annual litter fall, enabled the sequential loss of biomass and nutrients (phosphorus and nitrogen) to be reconstructed in undisturbed litter layers of Banksia ornata in the Dark Island heathland, South Australia.

Apart from an initial loss in biomass and nitrogen, the dry weight and nutrient content of the O1 layer, exposed to the desiccating influence of the atmosphere, remained relatively constant until covered by the following year's leaf fall. Under the blanket of newly fallen leaves, biomass decomposition proceeded continuously through autumn, winter, spring, into the dry summer season. Even though the biomass of the decomposing leaf (O2) layer decreased continuously, its nutrient content remained relatively constant until the summer season was reached when total decomposition and nutrient loss occurred.

During spring, fine rootlets invaded the decomposing litter layer (O2) and, together with decomposer fungi, bacteria and soil fauna, maintained the total nutrient content of the decomposing leaf at a constant level. By late spring-early summer shoot growth of the dominant heath species was initiated, inducing the mobilization of the nutrients stored in the decomposing litter layer.