Ecological relationships among hypogeous fungi and trees: inferences from association analysis integrated with habitat modeling

Association analyses by contingency tables and generalized linear modeling were compared to infer relationships among hypogeous (belowground-fruiting) ectomycorrhizal fungi and potential host tree species from 136 study plots in forested habitats in southeastern mainland Australia. Results from both types of statistical approaches were highly congruent. As with previous experimental studies, no exclusive fungus-host tree associations were identified. However, the likelihood of occurrence of some species of fungi increased significantly in the presence of particular host tree species, suggesting fungal host preference or shared habitat preferences. Similarly, while most associations among fungal species were nonsignificant, a few taxa were more likely to be found in the presence of certain others. These were termed positively associated and are thought to share common climatic and microhabitat requirements or host preferences. In contrast, other combinations of fungal species were negatively associated with one another, perhaps indicating different habitat preferences. Furthermore, the finding that some fungi occurred more frequently in the presence of certain tree species provides a starting point for selection of compatible host-fungus combinations that could be used for forest nursery and restoration applications.