Long-term effects of frequent burning on fungal communities and the role of fungi in fire-prone forests

© 2007 Dr. Madeleine Letitia Isaacs OsbornBushfire is an integral part of the Australian environment. Animals and plants show adaptations to and dependence on fire and prescribed burning is an important management tool in eucalypt forest ecosystems. Responses of flora and fauna to fire regimes have been extensively examined in Australian forests, however one aspect of the biota abundant within all forest types that has received little consideration is fungi. Despite their undoubted ecological significance, little is known regarding the taxonomy, biology and ecology of fungi, let alone the impact of fire upon fungal communities. Knowledge of the responses of fungi to fire is of intrinsic interest and is essential for effective forest management. Fungi have significant roles in transporting, storing, releasing and recycling nutrients. Consequently, disturbances such as fire that impact upon fungi and their ability to perform these ecosystem processes may be of importance to forest structure, health, productivity and sustainability. The aim of this study was to investigate the effects of repeated low-intensity prescribed burning on various aspects of the fungal community in two Australian eucalypt forests. Such research was deemed necessary to fill a significant gap in current knowledge regarding fungal ecology and to provide forest managers with recommendations for use of prescribed burning to enhance fungal biodiversity. Current knowledge of fungal community structure, function and contributions of fungi to forest ecosystem processes was explored, with a range of traditional and new techniques used to assess quantitative, qualitative and functional aspects of above- and belowground fungal communities. The diverse methods used enabled comprehensive assessment of numerous community dynamics and their application throughout the study was evaluated. Cost analysis showed that assessment of diversity and functional diversity of aboveground sporocarps was far more expensive than analysis of belowground fungal diversity. It was therefore suggested that future research should consider the relevance of aboveground sporocarps in the overall fungal community and that more attention should perhaps be given to diverse, abundant and functionally significant soil fungi. Assessment of fungal communities was undertaken in relation to experimental burning treatments within eucalypt forests and the influence of fire on vegetation, fuel and soil characteristics. Little overall difference was observed in richness and diversity of sporocarp morphotypes and functional groups among treatments in the Wombat Forest. No significant differences were observed among soil fungal biomass as indicated by ergosterol concentration in either Bulls Ground or Wombat Forest soils. In addition, molecular data showed that richness and diversity of soil fungi among treatments were similar and that no specific fungal community was associated with soils of any particular treatment in the Wombat Forest. Such findings suggest that low-intensity prescribed burning has little long-term effect on these aspects of the fungal communities investigated in Wombat Forest and Bulls Ground study areas. However, given the critical roles of fungi within ecosystem processes it could be assumed that even minor changes in community dynamics may be of functional significance within forests. It was therefore considered too presumptuous for the current study to offer management recommendations based on these findings and was suggested that further understanding of relationships between fungal diversity, functional groups and ecosystem function is necessary for appropriate management decisions and development of sustainable forests