Phyllosphere fungi on leaf litter of Fagus crenata: occurrence, colonization, and succession

Phyllosphere fungi occur on various litters, but the ecology of these fungi on leaf litter has received little attention. To investigate the occurrence, colonization, and succession of phyllosphere fungi on leaf litter of Fagus crenata Blume, fungi were isolated from living, senescent, freshly fallen, and decomposing leaves by surface sterilization and washing methods. A total of 18 and 47 fungal species were isolated from the interior and surface of living and senescent leaves, respectively, and 15 frequent species were regarded as phyllosphere fungi. These fungi were divided into three groups according to their frequency on freshly fallen and decomposing leaves. Nine species (Group I) occurred frequently on decomposing leaves, two species (Group II) on freshly fallen leaves only, and four species (Group III) were frequent on living or senescent leaves only. Colonization of sterilized, freshly fallen leaves by phyllosphere fungi was investigated to test their ability to infect litter directly after litter fall. Frequencies of four species were lower on sterilized leaves than on unsterilized leaves, whereas frequencies of other species did not differ between sterilized and unsterilized leaves. Successional trends of endophytes and epiphytes were observed during decomposition from freshly fallen to decomposing leaves. The sum of frequencies of endophytes decreased temporarily on freshly fallen leaves and increased on decomposing leaves. The sum of frequencies of epiphytes decreased from freshly fallen to decomposing leaves.