Allocasuarina tree hosts determine the spatial distribution of hypogeous fungal sporocarps in three tropical Australian sclerophyll forests

Abstract

Across three tropical Australian sclerophyll forest types, site-specific environmental variables could explain the distribution of both quantity (abundance and biomass) and richness (genus and species) of hypogeous fungi sporocarps. Quantity was significantly higher in the Allocasuarina forest sites that had high soil nitrogen but low phosphorous. Three genera of hypogeous fungi were found exclusively in Allocasuarina forest sites including Gummiglobus, Labyrinthomyces and Octaviania, as were some species of Castoreum, Chondrogaster, Endogone, Hysterangium and Russula. However, the forest types did not all group according to site-scale variables and subsequently the taxonomic assemblages were not significantly different between the three forest types. At site scale, significant negative relationships were found between phosphorous concentration and the quantity of hypogeous fungi sporocarps. Using a multivariate information theoretic approach, there were other more plausible models to explain the patterns of sporocarp richness. Both the mean number of fungal genera and species increased with the number of Allocasuarina stems, at the same time decreasing with the number of Eucalyptus stems. The optimal conditions for promoting hypogeous fungi sporocarp quantity and sporocarp richness appear to be related to the presence and abundance of Allocasuarina (Casuarinaceae) host trees. Allocasuarina tree species may have a higher host receptivity for ectomycorrhizal hypogeous fungi species that provide an important food resource for Australian mycophagous animals.

Key words:

• altitude
• ectomycorrhiza
• mycophagy
• nitrogen
• phosphorous

Acknowledgments

Financial support was provided by the Rainforest Cooperative Research Centre, Queensland Parks and Wildlife Service, and the School of Marine and Tropical Biology, James Cook University, Australia. Special thanks for expert taxonomic assistance to Dr Teresa Lebel of the Royal Botanic Gardens, Melbourne, Australia and Dr James Trappe of the Department of Forest Science Oregon State University, Corvallis. Statistical advice from Dr Will Edwards and Dr Darrell Kemp was very much appreciated. This project could not have been completed without assistance from, Mr Peter Latch and Dr John Winter of the Queensland Parks and Wildlife Service and these volunteers, E. Davis, A. Koetz, S. Mathams, Z. Hegedus, D. Murphy, F. duc-Goninaz, A. Mckinnon, A. Sakamoto, B. Paulus, C. Fairweather, J. Paul, L. Wenitong, L. Derby, L. Jones, P. Voigt, R. Rader, S. Spena, Z. Baron, S. Walker, B. Tilse, G. Kading, M. Barker, S. McMullan-Fisher, B. Bateman, K. Kong, N. Babiuk, M. Koch, P. Siemsen, A. Grimley, S. Carroll, S. Foley, D. Maltomini and P. Ortega. Scientific Purposes and Collection Permits (WISP01562903, WITK01565603) were issued by the Environmental Protection Agency and permission to collect (ATH 06/003, 05/005, 03/043) in state forest by the Queensland Parks and Wildlife Service. This project complied with all Australian laws and standards.