@article {bnh-7889, title = {Optimisation of fuel reduction burning regimes for fuel reduction, carbon, water and vegetation outcomes {\textendash} final project report}, number = {648}, year = {2021}, month = {03/2021}, institution = {Bushfire and Natural Hazards CRC}, address = {Melbourne}, abstract = {

Fire managers often have multiple objectives for a given prescribed burn centred around risk reduction and conservation of biodiversity. The ability to predict the effects of prescribed burning on the capacity of forests to deliver ecosystem services such as clean air, carbon sequestration, and a reliable and high-quality supply of water is becoming increasingly more important.

The body of research detailed in this Synthesis Report represents a concerted effort to understand the effect of prescribed burning on water quantity and carbon losses and gains in forested ecosystems in south-eastern Australia. We collected empirical data from over 100 sampling sites treated with a recent prescribed burn. The sampling strategy we used was consistent over time with target sampling variables included for estimation of overstorey and understorey biomass and direct sampling of surface and near surface fuel loads. Site selection was stratified to accommodate as much site variability as possible and to take full advantage of prescribed burn plans.

Data collected from the field was used in a variety of modelling assignments to capture the effect of prescribed burning on changes in water availability and transformation of carbon pools. Using a mixture of models and empirical sampling and analysis, we showed that there are few risks to long-term carbon and water cycles when prescribed burning is conducted on cycles of 10 or so years. Critical to this analysis is the frequency of bushfires {\textendash} if the inter-fire interval of unplanned fires becomes short (e.g., \<50 years) then ecosystem losses of carbon and reductions in water yield are likely to become semi-permanent features.

Our modelling endeavours ranged from relatively complex process-based models describing water and carbon balances through to simple response surface models. By exploring the transformation of carbon pools in surface fuels during prescribed burning, we developed robust yet simple-to-use models for predicting changes in total carbon and biomass in this fuel fraction. The novel application of FullCAM, a well-established model used for carbon accounting, was tested for its ability to incorporate often subtle changes in forest growth and carbon transformation associated with prescribed burning. We found this model to be relatively sensitive and recommend it to fire managers for applications such as estimation of carbon emissions. Based on our key findings, we advocate for continued research and evidence-based application of prescribed burning as a valuable land management approach.

Data assembled from peer-reviewed publications and researchers worldwide was mined for changing trends in publications concerning prescribed burning, global patterns of litterfall and standing litter, and water use efficiency of forests. These summative studies informed our research direction and chartered our progress.

A considerable number of student projects have been supported during the course of this project contributing to the training of the next generation of researchers and land managers.

}, keywords = {burning regimes, carbon, fuel reduction, optimisation, vegetation, water}, issn = {648}, author = {Bell, Tina and Adams, Mark A. and Mathias Neumann and Danica Parnell and David Pepper and Malcolm Possell} }