Fruiting of putative ectomycorrhizal fungi under blue gum (Eucalyptus globulus) plantations of different ages in Western Australia

The species richness of putative ectomycorrhizal (EM) fungi fruiting in blue gum (Eucalyptus globulus Labill.) plantations in Western Australia was investigated in relation to plantation age. Eleven plantations, 1-8 years old, were selected for study and two native Eucalyptus forest sites in the same region were chosen for comparison. Sporocarps of 44 species of putative EM fungi were collected from the 13 sites. Of these, 30 species were found in blue gum plantations. The number of fungal species was highly positively correlated with plantation age and inversely correlated with soil pH. Young plantations (1-5 years) had 2-9 fungal species and were overwhelmingly dominated by species of Laccaria and Scleroderma. In older plantations (6-8 years), the relative abundance of sporocarps of each species within the fungal community decreased, accompanied by an increase in the number of fungal species (12-17 per site). A brief survey of the two native eucalypt forests in this region revealed a much higher number of fungal species than that observed in plantations. In plantations, species of Descolea, Laccaria in, Pisolithus and Scleroderma typically fruited in young plantations. Species of epigeous fungi of the genera Boletus, Cortinarius, Hydnum, Inocybe, Lactarius, Paxillus, Russula and hypogeous fungi, including species of Descomyces, Hysterangium and Mesophellia, were found only in older plantations, or in native forests. Some of the fungi that fruit in young plantations are now being evaluated for use in commercial spore inoculation programs to increase the species diversity of EM fungi in exotic eucalypt plantations.