Biologue

Article by
Andrew Claridge, NSW National Parks and Wildlife Service, PO Box 2115, Queanbeyan NSW 2620

Dr Andrew Claridge of the NSW National Parks and Wildlife Service and Dr Jim Trappe of Oregon State University have received $13,000 for two years to explore the diversity and habitat requirements of the important, truffle-like mycorrhizal fungi in mainland south-eastern Australia. These fungi serve as a major food source for a range of terrestrial mammals. The many new fungal taxa so far discovered will be published in generic monographs. Habitat requirements for major species are also being modelled for use in forest management to enhance this important food base for wildlife.

Most bush walkers in Australia's forest don't realize that below the ground on which they tread hides a treasure of fungi. Amongst these, the sequestrate, or truffle-like fungi play particularly important roles in the forest web of life. Their mold growth connects tree roots to the soil, and it is through these fungal filaments that the tree acquires most nutrients. Their small, potato-like fruiting bodies are a major food source for native mammals, including bandicoots, potoroos and rodents. These fungi, in turn, rely on being eaten by the animals for dispersal of spores: the animal digests all the fruiting body except the spores, which pass through the digestive tract to be deposited on the forest floor in faecal pellets.

The project consists of 134 plots, each 50 x 20 m, selected to represent a wide range of vegetation types, soils and climates in south-eastern mainland Australia. Plots have so far been sampled 4 times by a time-constraint procedure, beginning in 1996. The plots are raked about 2-4 cm into the mineral soil, and all fruiting bodies found are collected and bagged by species. In about a year the raked areas are barely noticeable, and after 2 years the sites have fully recovered. Detailed data on habitat characteristics are recorded for each plot for the habitat modelling exercise.

Although Drs Claridge and Trappe expected a satisfying variety of these fungi, the diversity encountered over the study sites has been astonishing. So far the researchers have identified nearly 60 genera, of which at least 10 are new to science. Of the more than 200 species identified, at least 125 are undescribed. Monographs of these new taxa are being prepared for publication in the scientific literature. Although the data are not yet fully entered on a database, it appears that some plots may have well over a dozen species. Most are endemic to Australia, although many of the genera occur on other continents. Statistical analyses reveal that some species are regularly associated with others. For example, Cortinarius globuliformis and Chamonixia vittatispora regularly occur on the same sites; indeed their fruiting bodies are often intermingled.

Sampling of the plots is expected to continue for the foreseeable future, on a two-yearly basis, to better document long-term patterns in the diversity and occurrence of sequestrate fungi in our Australian temperate forest environments.