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Ms Bryony Horton

profile_horton_thumbMs Bryony Horton
PhD student

Topic: fire management and tree decline:
mycorrhizal indicators of declining forest health

University of Tasmania

 

Decreasing health of mature trees leading to premature death, known as "tree decline", is widespread throughout Australia and is a serious problem effecting both conservation and economic management of eucalypt forest.

One eucalypt species affected, Eucalyptus delegatensis, occurs in high altitude forest in Tasmania. Recent theories link eucalypt tree decline with changes in fire management - from frequent burning by Aborigines in the past, to an absence of fire under European management. In high altitude forests where fire has been excluded, evidence suggests that eucalypt dieback is associated with the invasion of rainforest understorey plants, and that dieback is reversed after fire. Many other environmental and biological variables, such as soil characteristics, are also likely to change with an absence of fire.

Mycorrhizal fungi are an important component of Australian forests and live symbiotically with eucalypts on their roots, helping the trees to absorb nutrients, protecting them from pathogens and reducing toxicity. Previous research has indicated that there are associated changes in the fungal community when a forest is in decline. Fungal community structure changes over time after fire, possibly also influencing other ecosystem processes like nutrient cycling and plant dynamics.

My research project aims to link changes in the mycorrhizal community of E. delegatensis forest to the distribution of understorey plants (sclerophyll and rainforest) that represent increasing time since fire. Other co-variables to time since burnt include soil factors and canopy condition (which will be used as an indicator of decline) and these will also help explain any identified differences. The impact of fire on the mycorrhizal community will also be investigated.

I will use molecular profiling techniques to analyse samples of different mycorrhizal fungus species. Samples will be collected from burnt and unburnt forests with either sclerophyll or rainforest understorey.

This project will help to establish the role of mycorrhizal fungi in the maintenance of healthy forests. It would be a major achievement to identify indicators of forest health within the mycorrhizal community that aid the long term sustainable management of healthy forests.

I first studied mycorrhizal associations for my Honours project at the University of New South Wales (UNSW) in 2002. Since then I have mostly worked in botany and vegetation management and have occupied a variety of posts including further mycorrhizal research at UNSW, plant taxonomy with Sydney Royal Botanic Gardens, ecological monitoring in the UK for The Wildlife Trust, botanical consultancy in the private sector and on various urban revegetation projects. I moved to Hobart early 2006 but quickly relocated to Maatsuyker Island where I spent an unbelievable four months before beginning my PhD in July 2006.

My supervisors are Dr Neil Davidson (School of Plant Science, University of Tasmania), Dr Morag Glen (Ensis), Associate Professor Caroline Mohammed (School of Agricultural Science, University of Tasmania) and Dr Tim Wardlaw (Forestry Tasmania).

My PhD studies contribute to CRC for Forestry Biodiversity project 4.2 and project B7 of the Bushfire CRC.

To browse other PhD projects available with the CRC for Forestry, click here.

My project is funded by the Bushfire CRC, the University of Tasmania and the Holsworth Wildlife Research Trust, with contributions and support from Forestry Tasmania and the CRC for Forestry.