ICOM1 Abstract

talk session 4 BRUNDRETT, MARK. CSIRO Forestry and Forest Products, Private Bag, PO, Wembley, Western Australia, 6014, Australia. - The ecology of VAM fungi in undisturbed and disturbed habitats in tropical Australia The diversity and distribution of Glomalean fungi forming VAM associations were examined in undisturbed and disturbed habitats in the vicinity of Kakadu National Park in tropical Australia. Methods used to examine fungal populations in soils included (a) Spore numbers (b) spore biovolumes (c) identification of fungi by colonisation patterns in bioassay plant roots and (d) isolation of fungi in pot cultures. Topsoil was collected from 32 sites, including eucalypt savanna, rocky hill, wetland, rain forest and minesite rock dump habitats. 15 species of VAM fungi were identified from spores found in these samples and 7 additional fungi were recovered from the same soils using 4 complimentary pot culturing methods. Different methods of detecting fungi produced different answers about which fungi were most important in soils. Undisturbed sites contained between 7 and 12 species of VAM fungi, but disturbed sites had a much lower diversity. Most species were widespread, but some only occurred in disturbed habitats or waterlogged soils. Fungi were associated with patches of vegetation in disturbed habitats and the abundance of their spores and other propagules increased with plant cover, reaching levels well in excess of those found in undisturbed plant communities. Bioassay results for different genera of VAM fungi were well correlated with spore numbers, but not biovolume data. Differences in propagule strategies suggest that fungi had different life history categories, that corresponded with genera or groups within genera. Observations of fungi in pot cultures provided valuable information about spore features, spore size, spore numbers, external hyphae, vesicles, etc.