Soil fungal communities differ in native mixed forest and adjacent Araucaria cunninghamii plantations in subtropical Australia

Purpose Commercial monoculture plantations of the native Australian Araucaria cunninghamii are common in subtropical and tropical Queensland and are generally established following clearing of native mixed forest. The consequences of such forest conversion for soil fungal communities, however, have not been assessed in detail. Materials and methods We utilised direct DNA extraction from soil coupled with terminal restriction fragment length polymorphism (T-RFLP) analysis of rDNA internal transcribed spacer (ITS) regions to investigate soil fungal community structure under native mixed forest and first and second rotation A. cunninghamii plantations at Yarraman State Forest, Queensland, Australia. We also investigated the influence of forest harvest residue windrows on soil fungi in a second rotation A. cunninghamii plantation and compared soil fungal communities in soil with those in sand-filled hyphal ingrowth bags buried at the site. Results and discussion Ordination analysis of the fungal community T-RFLP data indicated significant separation of native forest soil samples from the plantation forest soil samples along canonical axis 1, while with first rotation plantation forest soil samples separated from second rotation forest soil samples along canonical axis 2. Fungal communities in soil and hyphal ingrowth bag samples were also shown to differ significantly for the three forest types, suggesting that the hyphal ingrowth bags selected for certain fungi at the site. Windrow soil samples did not separate significantly from nonwindrow soil samples in the second rotation A. cunninghamii plantation. Mean terminal restriction fragment numbers were significantly lower in the A. cunninghamii plantation samples than in the native forest samples and lower in the second rotation than the first rotation plantations. Terminal restriction fragment numbers were also lower in the hyphal ingrowth bag samples than in the respective soil samples. Analysis of cloned ITS sequences indicated that Ascomycota were most abundant, followed by Basidiomycota and Zygomycota; however, their relative importance varied in the different forest types. Conclusions Overall, the data suggest that conversion of native mixed forest to A. cunninghamii plantations changes soil fungal community composition and that the effect is more pronounced in second rotation forests.