@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} } @article {bnh-6905, title = {Detecting the effects of prescribed burning using generalised additive modelling}, number = {566}, year = {2020}, month = {05/2020}, institution = {Bushfire and Natural Hazards CRC}, address = {Melbourne}, abstract = {

Data collected from 52 plots from sites in Victoria and New South Wales were used to test whether a simple modelling technique {\textendash} a generalised additive model (GAM) {\textendash} could be used in conjunction with satellite imagery to detect the effect of prescribed burning on the hydrological cycle. Evapotranspiration (ET) was selected as the strongest indicator of a change in forest hydrology given the direct effect of removal of vegetation with fuel reduction burning. Variables included in the ET GAM were site details (location, elevation, aspect, slope), soil properties (total carbon and nitrogen), climate (short-term and long- term rainfall, maximum and minimum daily temperature, solar radiation) and the enhanced vegetation index (EVI), a commonly used spectral product derived from satellite imagery. These variables were used to develop GAMs using sites in each state and combined together. Results from this modelling suggested a change in ET due to prescribed burning was more obvious for sites in Victoria than in NSW. Vegetation (EVI) and climatic variables (solar radiation, df5 and df95) were the best predictors for changes in ET due to prescribed burning activities. Soil (C:N) and terrain variables (slope, aspect, elevation) were not important factors for detecting change in ET. Limitations due to temporal and spatial differences in sampling unburnt and burnt plots and future potential for this method are discussed.

}, keywords = {additive modelling, fire effects, Prescribed burning}, issn = {566}, author = {Mengran Yu and David Pepper and Bell, Tina and Malcolm Possell} } @article {bnh-7030, title = {Model predictions for fuel reduction burning of eucalypt open forest in the greater Blue Mountains region}, number = {587}, year = {2020}, month = {07/2020}, institution = {Bushfire and Natural Hazards CRC}, address = {Melbourne}, abstract = {

Prescribed burns are a land management tool used for reducing fuel loads in terrestrial ecosystems. Under extended drier, hotter weather conditions they might be used increasingly and more widely to help manage risk of wildfire and subsequent damage to life, property and natural assets. They also represent a form of disturbance to ecosystems, including their biodiversity and biogeochemistry. From a biogeochemistry perspective, we apply the FullCAM carbon accounting model to eucalypt open forest sites in the greater Blue Mountains region that underwent prescribed burns and fieldwork campaigns in 2019. Field data were used to derive values and estimates that guided model calibration and helped to explore the suitability of FullCAM for simulating the effect of prescribed burning on this ecosystem type. The diameter at breast height of overstorey and understorey trees, leaf area index and surface litter fractions were key measurements for estimating production, allocation, turnover (litter input to surface debris) and breakdown (output from surface debris) of carbon pools of forest components and hence, for calibrating FullCAM. Measurements for paired burnt/unburnt plots were key to estimating loss of carbon from forest component pools to the atmosphere due to prescribed fire. Simulation of unburnt forest component pools were reasonable as a calibration, although improvements in simulating fractions of surface litter would probably improve simulations of the effect of prescribed fire on forest component pools. Recommendations related to collection of field data and to model structure are made to improve alignment between model-data comparisons.

}, keywords = {Blue Mountains, eucalypt, Fuel reduction burning, modelling, open forest, predictions}, issn = {587}, author = {David Pepper and Bell, Tina and Malcolm Possell and Danica Parnell} } @article {bnh-5619, title = {Modelling emissions from prescribed burning using FULLCAM}, number = {479}, year = {2019}, month = {06/2019}, institution = {Bushfire and Natural Hazards CRC}, address = {Melbourne}, abstract = {

The Full Carbon Accounting Model (FullCAM) is a software tool developed by the Australian Government, Department of the Environment and Energy as a standard method for carbon accounting. It is primarily used as a means to report national\ greenhouse gas dynamics from the land sector due to anthropogenic activities. This\ study assessed the accuracy and usefulness of FullCAM in determining the mass of carbon (C) emissions produced from prescribed burning. FullCAM proved to be a simple and reasonably reliable method for estimating C emissions from prescribed burning activities and for tracking recovery of C pools related to forest ecosystems. In addition, C emissions from different prescribed burning scenarios and from wildfire can be easily compared. The FullCAM model can be used by land managers as a means to manage an important aspect of risk associated with planned burning. If land managers are required to perform C accounting activities in the future, the adoption of FullCAM will enable them to be compatible with the national standard of carbon accounting.

}, keywords = {Bushfire, emissions, FullCAM, modelling, Prescribed burning}, issn = {479}, author = {Senani Karunaratne and Malcolm Possell and David Pepper and Bell, Tina} }