Fungal colonization of phyllosphere and litter of Quercus rotundifolia Lam. in a holm oak forest (High Atlas, Morocco)

The microfungal flora of holm oak living, senesced and litter leaves was studied at five different stages of decomposition using three different isolation methods. Holm oak leaves are first colonized on the tree by a variety of primary saprophytes such as Trichothecium, Aureobasidium, Cladosporium, Epicoccum and Alternaria. After leaf fall there is an intensive development of the fungal flora, including both species already present in the phyllosphere and new colonizers from the litter layer. With increasing decomposition initial colonizers gradually disappear, being replaced by other forms. When all isolation methods were pooled, maximum biodiversity (species richness) of the fungus flora was observed during the first three stages of leaf litter decomposition, but strong variation occurred according to the isolation method. Sterilization of the leaf material revealed that a number of fungal strains were present inside the holm oak leaves before abscission, increasing from living to senescent stages, and that a strong decrease in the internal colonization of leaf litter was observed at late decomposition stages.