Diversity and habitat relationships of hypogeous fungi. II. Factors influencing the occurrence and number of taxa

Fruit-bodies of hypogeous fungi were sampled over two seasons across 136 forested study sites representing a stratified sample of the climatic, geological and topographic features of far south-eastern mainland Australia. Two hundred and nine species, over three-quarters being undescribed, were recorded. Statistical models based on various environmental attributes measured for each site were developed for the occurrence of several common taxa. At a landscape scale, climatic factors such as mean minimum temperature of the coldest month and annual mean moisture index were important explanatory variables for most taxa examined, but the type of response varied. More locally, topographic position, soil fertility, time since last fire and micro-habitat structures such as the leaf litter layer and number of large fallen trees also influenced the distribution of taxa in different ways. A model was then developed for the number of fungal species occurring at each site. Important explanatory variables were type of substrate, topography and diversity of potential host eucalypt species. The utility of each model constructed needs evaluation by further sampling of hypogeous fungi. Possible implications of our findings for forest management are discussed. Further analyses of our existing data are also identified.