@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-7029, title = {Estimating carbon stocks and biomass in surface fuel layers}, number = {586}, year = {2020}, month = {07/2020}, institution = {Bushfire and Natural Hazards CRC}, address = {Melbourne}, abstract = {

In this report we describe a simple model that can be used to estimate carbon

(C) stocks in surface fuel layers for C accounting purposes. We used empirical data collected from dry sclerophyll forests from a range of sites in Victoria, New South Wales and the Australian Capital Territory. This information was used to develop an easy-to-use tool to improve estimates of C emissions from prescribed burning. Models developed using data from each state have been reported previously {\textendash} here we present an evaluation of a universal model developed using the complete empirical dataset for all sites in all three states, and two separate models ({\textquoteleft}universal{\textquoteright} models) developed using data from all the sites burnt by prescribed fires and nearby unburnt sites.

Samples of the near-surface fuel layer were separated into three fractions: fine fuel (\<9 mm diameter), intact leaves, and twigs and other material such as fruits, flowers and bark. The dry weight and C content of each fraction was determined. To model biomass and C content of surface fuels, a mixture design was used. For each site, the proportion of the total fuel load of each of the three surface litter fractions was used as an independent factor (x1, x2, and x3), and the corresponding total fuel load (t ha-1) or C content (t C ha-1) was used as the dependent factor. A response surface was fitted to the mixture design using a Generalised Blending Mixture model (GBM) and a polynomial equation for each response was generated by running the GBM with varying numbers of terms included in the response surface equation. To determine the best fitting equation, Akaike information criterion (AICc) was used as a measure of the relative quality of the response surface for a given set of data in relation to other model iterations. Data were randomly assigned into an 80:20 split for training and testing of the response surface of the model. Models were also validated against a second set of data collected from high and low productivity forest sites. This additional information improved data spread and, thus, model testing.

The response surfaces fitted to data showed reasonable agreement with the data but the universal model (burnt and unburnt data from all sites combined) tended to be unreliable with both over- and underpredictions depending upon which dataset was being used for testing or validation. Universal models created using data from all burnt or unburnt sites were better than other trained models for predicting of biomass or C content in relation to fire history.

}, keywords = {biomass, carbon stocks, estimates, surface fuel layers}, issn = {586}, author = {Danica Parnell and Malcolm Possell and Bell, Tina} } @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-6907, title = {Near infrared spectroscopy as a new fire severity metric}, number = {568}, year = {2020}, month = {05/2020}, institution = {Bushfire and Natural Hazards CRC}, address = {Melbourne}, abstract = {

Samples of leaves, twigs and bark representing typical surface fuels from forests and woodlands were systematically heated until combusted under controlled conditions in the laboratory. Change in colour of residue was described using R-conversion of the Munsell colour system and compared to colours generated from near infrared (NIR) scanning. Regardless of the method of heating used, there was very little change in physical properties or colour of residues when heated at low temperatures to 200

{\textdegree}C. Surface fuel samples began to thermally degrade when heated at 300 {\textdegree}C, which was reflected in much darker coloured residues that were mostly uniform in colour for different fuel types when determined from NIR spectroscopy. When surface fuels were combusted at temperatures between 400 and 600 {\textdegree}C, residues were much lighter in colour regardless of the type of fuel burnt. Again, residue colours were more uniform when described using NIR spectroscopy compared to the Munsell colour system, although differences in the consistency of residues (heterogenous production of charred material and ash) were still reflected in variations in shading. In several instances, colours resulting from NIR scans were closer to the actual colour of residues suggesting that it is a more accurate system than colour matching by eye using the Munsell colour system.

This study indicates that there is potential for NIR technology to be used to determine fire severity according to the colour of residue after fire. While the general method of colour matching is not new, the use of NIR spectroscopy can reduce inaccuracies associated with subjective colour matching and poor colour correlation when using some forms of automated colour conversion. As shown, spectroscopic methods such as NIR can also be used to assess chemical changes in fuels during thermal decomposition. This includes quantitative losses of carbon and nitrogen and estimating fire intensity according to the temperature that were required to form a particular residue.

}, keywords = {fire severity, infrared, metrics, spectroscopy}, issn = {568}, author = {Danica Parnell and Bell, Tina and Malcolm Possell} } @article {bnh-6902, title = {Non-Additive Effects of Forest Litter on Flammability}, journal = {Fire}, volume = {3}, year = {2020}, month = {05/2020}, abstract = {

Forest litter is a fuel component that is important for the propagation of fire. Data describing fuel load, structure and fuel condition were gathered for two sites of Sydney Coastal Dry Sclerophyll Forest, a common vegetation type in the Sydney Basin, Australia. Surface litter from the sites was sorted into its constituent components and used to establish which component or mixture of components were the most flammable using several metrics. A general blending model was used to estimate the effect the different mixtures had on the response of the flammability metrics and identify non-additive effects. Optimisation methods were applied to the models to determine the mixture compositions that were the most or least flammable. Differences in the flammability of the two sites were significant and were driven by\ Allocasuarina littoralis. The presence of\ A. littoralis\ in litter mixtures caused non-additive effects, increasing the rate of flame spread and flame height non-linearly. We discuss how land managers could use these models as a tool to assist in prioritising areas for hazard reduction burns and how the methodology can be extended to other fuel conditions or forest types.

}, keywords = {Bushfire, general blending model, land management, non-additive effect, prescribed burn, simplex centroid design}, doi = {https://doi.org/10.3390/fire3020012}, url = {https://www.mdpi.com/2571-6255/3/2/12}, author = {Angela Gormley and Bell, Tina and Malcolm Possell} } @article {bnh-6978, title = {Quantifying the conversion of vegetation to ash for soil carbon fingerprinting}, number = {572}, year = {2020}, month = {06/2020}, institution = {Bushfire and Natural Hazards CRC}, address = {Melbourne}, abstract = {

Samples of leaves, twigs and bark representing typical surface fuels from forests and woodlands were systematically heated and combusted under controlled conditions. Very little biomass, carbon (C) and nitrogen (N) was lost when heated at low temperatures to 200 {\textdegree} and greatest losses occurred between 400 and 600

{\textdegree}C, regardless of the type of fuel burnt. Losses of C and N varied considerably with temperature. Carbon was lost when fuels were heated at temperatures of 300 {\textdegree}C or more. Nitrogen was relatively more abundant when heated at 400 {\textdegree}C, albeit at very low levels (less than 5\%). When heating time was varied there were noticeable differences in patterns of weight loss and changes in proportions of C and N. This indicates that both fire intensity and residence time is likely to be important in understanding losses of C and nutrients during fire, particularly during low intensity prescribed burning.

The use of colour of residues after heating surface fuel has the potential to determine fire severity. Existing technology such as near infra-red scanners can measure ash colour, not only indicating fire severity but also, by association, C and N losses from fire. Combustion studies done in a well-controlled laboratory environment could be used to interpret fireground conditions in relation to fire intensity and residence time, according to the nature and amount of charred material, charcoal and ash that remains after fire.

}, keywords = {Ash, milestone, soil carbon fingerprinting, vegetation}, issn = {572}, author = {Danica Parnell and Bell, Tina and Malcolm Possell} } @article {bnh-6980, title = {Sampling and data analysis of field sites of 40 prescribed burns}, number = {573}, year = {2020}, month = {06/2020}, institution = {Bushfire and Natural Hazards CRC}, address = {Melbourne}, abstract = {

This report provides a summary of the main features of the sites sampled as burn units in the Blue Mountains, NSW to characterise the biomass, carbon and nitrogen held in vegetation/fuel in unburnt and burnt sites. Sites sampled in Victoria and NSW for refinement and testing of current surface fuel models is also provided. Details of how empirical data collected from the field has been used in our modelling efforts and in student projects has been provided.

}, keywords = {data analysis, field sites, prescribed burns, sampling}, issn = {573}, author = {Bell, Tina and Danica Parnell and Malcolm Possell} } @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} } @article {bnh-5094, title = {Can a growth model be used to describe forest carbon and water balance after fuel reduction burning in temperate forests?}, journal = {Science of the Total Environment}, volume = {615}, year = {2018}, month = {02/2018}, pages = {1000-1009}, chapter = {1000}, abstract = {

Empirical evidence from Australia shows that fuel reduction\ burningsignificantly reduces the incidence and extent of unplanned fires. However, the integration of environmental values into\ fire management\ operations is not yet well-defined and requires further research and development.

WAVES, a plant growth model that incorporates Soil-Vegetation-Atmosphere Transfer, was used to simulate the hydrological and\ ecological effects\ of three fuel management scenarios on a\ forest ecosystem. WAVES was applied using inputs from a set of forest plots for one year after three potential scenarios: (1) all litter removed, (2) all litter and 50\% of the\ understorey\ removed, (3) all litter and understorey removed. Modelled outputs were compared with sites modelled with no-fuel reduction treatment (Unburnt).

The key change between unburnt and fuel reduced forests was a significant increase in soil moisture after fire. Predictions of the recovery of aboveground carbon as plant biomass were driven by model structure and thus variability in available light and soil moisture at a local scale. Similarly, effects of fuel reduction burning on\ water processes\ were mainly due to changes in vegetation interception capacity (i.e. regrowth) and soil evaporation. Predicted effects of fuel reduction burning on total\ evapotranspiration\ (ET) {\textendash} the major component of\ water balance\ {\textendash} were marginal and not significant, even though a considerable proportion of ET had effectively been transferred from understorey to overstorey. In common with many plant growth models, outputs from WAVES are dictated by the assumption that overstorey trees continue to grow irrespective of their age or stage of maturity. Large areas of eucalypt forests and woodlands in SE Australia are well beyond their aggrading phase and are instead over-mature. The ability of these forests to rapidly respond to greater availability of water remains uncertain.

}, doi = {https://doi.org/10.1016/j.scitotenv.2017.09.315}, url = {https://www.sciencedirect.com/science/article/pii/S0048969717326669?via\%3Dihub}, author = {Gharun, Mana and Malcolm Possell and R. Willem Vervoort and Adams, Mark A. and Bell, Tina} } @article {bnh-5033, title = {Sampling and data analysis of field sites in NSW}, number = {419}, year = {2018}, month = {10/2018}, institution = {Bushfire and Natural Hazards CRC}, abstract = {

Fuel reduction burning (FRB) is used as a risk mitigation strategy for unplanned fires by altering fuel loads and changing fire behaviour. This involves temporary removal of accumulated fuels of the near-surface and surface fuel layers (Fernandes and Herminio 2003). As the main intention of FRB is to reduce the risk to life and property, associated environmental impacts are often overlooked (Sohngen and Haynes 1997; Gharun et al. 2017a). Fire has a major role in altering biodiversity, carbon and hydrological balances, and can be the cause of soil erosion. As such, changes due to disturbance caused by FRB need to be investigated, and, where practical, integrated into management operations (Gharun et al. 2017a). As planning by fire agencies becomes more sophisticated and accountable, environmental management objectives for FRB need to consider maintenance of high-quality water sources, reduction of carbon dioxide (CO2) emissions and conservation of biodiversity.

}, author = {Bell, Tina and Danica Parnell and Malcolm Possell} } @article {bnh-3325, title = {Calibration of water balance using digital photography}, number = {241}, year = {2017}, month = {01/2017}, institution = {Bushfire and Natural Hazards CRC}, address = {Melbourne}, abstract = {

Prescribed fires impact the hydrological cycle in forested catchments because they remove vegetation and modify the amount of evapotranspiration (ET) that occurs. Evapotranspiration is the most important component of the hydrological cycle and perturbations to it can substantially affect the water balance of an ecosystem. However, our understanding of ET responses to disturbance is very limited and this makes post-fire assessment of water balance difficult.


In this study we used relationships between tree size and tree water use, and leaf area index (LAI) and forest water use to investigate the impact of fuel-reduction burning (FRB) on water availability. Leaf area index is an important input for estimating ET and measurement techniques such as digital photography can potentially be used by land managers as a means of rapidly quantifying the impact of FRB on water balance at both the plot- and catchment-scale. Our results will enable land managers to identify hydrologically sensitive areas in accordance with their management objectives.

}, issn = {241}, author = {Gharun, Mana and Malcolm Possell and Bell, Tina} } @article {bnh-3821, title = {Effects of Oxygen Concentration on Radiation-Aided and Self-sustained Smoldering Combustion of Radiata Pine}, journal = {Energy \& Fuels}, year = {2017}, month = {07/2017}, abstract = {

Smoldering combustion is an important form of combustion in wildfires and hazard reduction burning because it plays vital roles in pollutant emission, fire re-ignition, and ecological impact. Smoldering combustion can be classified as either radiation-aided or self-sustained, depending on the nature of the reactions. The latter is often considered a more hazardous type of smoldering combustion, because it can persist for a long period of time and can transition into flaming combustion. However, there is a lack of understanding of the differences between radiation-aided and self-sustained smoldering combustion processes, especially regarding characterization. The aim of this study is to investigate and quantify the differences between radiation-aided and self-sustained smoldering combustion in biomass. Experiments were conducted using an infrared heat lamp to heat pulverize fuel samples in a reactor. The external energy input and oxygen concentration were controlled in order to achieve radiation-aided and self-sustained smoldering combustion. Radiation-aided and self-sustained smoldering combustion were quantified based on temperature measurements in the reactor, the analyses of product gases, and the mass change of the testing samples. Under the current experimental conditions, self-sustained smoldering can only be initiated when the oxygen concentration is between 10\% and 21\%; only radiation-aided smoldering combustion can be initiated in oxygen concentrations under 7.5\%; and no ignition occurs when the oxygen concentration is equal to or less than 5\%. From the temperature measurements, there is a linear relationship between oxygen concentration and smoldering velocity.

}, doi = {10.1021/acs.energyfuels.7b00646}, url = {http://pubs.acs.org/doi/abs/10.1021/acs.energyfuels.7b00646}, author = {Wang, Houzhi and van Eyck, P. J. and Medwell, P. R. and Birzer, C. H. and Tian, Z. F. and Malcolm Possell} } @article {bnh-4118, title = {Improving forest sampling strategies for assessment of fuel reduction burning}, journal = {Forest Ecology and Management}, volume = {392}, year = {2017}, month = {05/2017}, pages = {78-89}, chapter = {78}, abstract = {

Land managers\ typically make\ post hoc\ assessments of the effectiveness of fuel reduction burning (FRB), but often lack a rigorous sampling framework. A general, but untested, assumption is that variability in soil and fuel properties increases from small (\~{}1\ m) to large spatial scales (\~{}10{\textendash}100\ km). Based on a recently published field-based sampling scheme, we addressed the following questions: (i) How much variability is captured in measurements collected at different spatial scales? (ii) What is the optimal number of sampling plots required for statistically robust characterisation of burnt areas? (iii) How can land managers improve their assessment of the effectiveness of FRB? We found that measurement variability does not increase with scale for all fuel components. Results showed that\ coarse woody debris\ is as variable at the small scale (plot, m) as it is at the landscape scale (km). For certain fuel components, such as litter biomass (in unburnt areas),\ overstorey\ biomass and leaf area, and\ soil properties\ such as total carbon and total nitrogen, samples taken at the small (plot) scale were indicative of variation at the larger scale of an individual FRB and more broadly across the landscape.

We then tested the hypothesis that site stratification can reduce variability between sampling plots and as a consequence will reduce the required number of sampling plots. To test this hypothesis we used Landsat Normalized Difference Vegetation Index (NDVI) across areas treated with FRB and compared the number of sampling plots required to estimate mean fuel biomass with and without stratification. Stratification of burnt areas using remotely sensed vegetation indices reduced the number of sampling plots required. We provide a model of green biomass from Landsat NDVI and make recommendations on how sampling schemes can be improved for assessment of fuel reduction burning.

}, doi = {https://doi.org/10.1016/j.foreco.2017.03.001}, url = {http://www.sciencedirect.com/science/article/pii/S0378112716310751?via\%3Dihub}, author = {Gharun, Mana and Malcolm Possell and Jenkins, Meaghan E. and Lai Fan Poon and Bell, Tina and Adams, Mark A.} } @conference {bnh-3875, title = {Modelling feedback between fuel reduction burning and forest carbon and water balance in eucalypt forests}, booktitle = {AFAC17}, year = {2017}, month = {09/2017}, publisher = {Bushfire and Natural Hazards CRC}, organization = {Bushfire and Natural Hazards CRC}, address = {Sydney}, abstract = {

Empirical evidence from Australia shows that fuel-reduction burning significantly reduces the incidence and extent of unplanned fires. However, the integration of environmental values into fire management operations is not yet well-defined and requires further research and development.

While in reality carbon and water processes in forested ecosystems are coupled, effects of fire on these processes are often studied in isolation. Models that simulate the dynamic interaction and feedbacks between these processes are essential for investigations of the effects of fuel management in an environmental setting.\ 

WAVES, a soil-vegetation-atmosphere transfer (SVAT) model, was used to simulate the hydrological and ecological effects of four fuel management scenarios on a forest ecosystem. WAVES was applied using inputs from a set of forest plots across south-east Australia for a period of 1 year after four potential scenarios: (1) no fuel- reduction treatment (unburnt), (2) all litter removed, (3) all litter and 50\% of the understorey vegetation removed, 4) all litter and all of understorey vegetation removed.

The impacts of fuel-reduction burning on water processes were mainly due to changes in vegetation interception capacity and soil evaporation. The effect of fuel-reduction burning on evapotranspiration is discussed considering the balance of vegetation biomass in the overstorey and the understorey. Recovery of aboveground carbon as plant biomass was strongly linked to variability in available light and soil moisture. We describe how these modelling efforts can be used for impact assessment in terms of water, vegetation and carbon outcomes for planning of fuel reduction burning.

}, author = {Gharun, Mana and Malcolm Possell and Bell, Tina} } @article {bnh-4117, title = {Optimisation of fuel reduction burning regimes for carbon, water and vegetation outcomes}, journal = {Journal of Environmental Management}, volume = {203}, year = {2017}, month = {12/2017}, pages = {157-170}, chapter = {157}, abstract = {

Fire plays a critical role in biodiversity, carbon balance, soil erosion, and nutrient and hydrological cycles. While empirical evidence shows that fuel reduction burning can reduce the incidence, severity and extent of unplanned fires in Australia and elsewhere, the integration of environmental values into fire management operations is not well-defined and requires further research and development. In practice, the priority for fuel reduction burning is effective mitigation of risk to life and property. Environmental management objectives, including maintenance of high quality water, reduction of CO2\ emissions and conservation of biodiversity can be constrained by this priority. We explore trade-offs between fuel reduction burning and environmental management objectives and propose a framework for optimising fuel reduction burning for environmental outcomes.

}, doi = {https://doi.org/10.1016/j.jenvman.2017.07.056}, url = {http://www.sciencedirect.com/science/article/pii/S0301479717307387?via\%3Dihub}, author = {Gharun, Mana and Malcolm Possell and Bell, Tina and Adams, Mark A.} } @article {bnh-3093, title = {Application of statistical techniques to pyrolysis-GC-MS data from soil to identify the impact of fire}, number = {226}, year = {2016}, month = {09/2016}, institution = {Bushfire and Natural Hazards CRC}, address = {Melbourne}, abstract = {

Soil organic matter has strong effects on many soil properties such as water holding capacity, soil structure and stability, nutrient availability and cation exchange capacity.\  Therefore, characterising soil organic matter is necessary to improve soil management.\  Pyrolysis coupled to gas chromatography-mass spectrometry (pyr-GC-MS) is one of many techniques that have been successfully used in this characterisation.\  However, a major limitation of pyr-GC-MS is that generates large amounts of mass-spectrometry data preventing fast, high throughput data analysis.\  This hinders our ability to identify compounds in complex matrices such as SOM that could be useful for predicting their characteristics.\  In this study, we aimed to investigate whether it was possible to rapidly identify significant differences among pyr-GC-MS data from soil from burnt and unburnt areas using an unsupervised statistical approach and identify the specific features that cause them.\  Of nearly 400 useful compounds extracted from the pyr-GC-MS data, only 15 were found to be necessary to classify between burnt and unburnt soil.\  We discuss how these features could be useful in the classification of soil disturbance such as fire or, potentially, as a quantitative measure of fire impact (intensity or severity).

}, author = {Malcolm Possell and Gharun, Mana and Bell, Tina} } @article {bnh-3956, title = {Identification and quantitative analysis of smoldering and flaming combustion of Radiata Pine}, journal = {Energy Fuels}, volume = {30}, year = {2016}, month = {07/2016}, abstract = {

Smoldering combustion is an important combustion process in wildfires; however, there are fewer experimental studies recorded in the literature in comparison with flaming combustion. An experimental study was conducted to characterize the initiation of smoldering and flaming combustion of biomass using temporal and spatial temperature profiles, mass loss profiles, and gas analyses. The results show that the peak temperature, temperature rise rate, and average mass loss rate of flaming combustion are much higher than those of smoldering combustion. The results on the ratio of CO to CO2\ for flaming and smoldering combustion show good agreement with the data reported in the literature. The results also show that smoldering combustion can be initiated only under a low air flow; for the experimental apparatus used, this corresponded to flow velocity of <=38.1 mm{\textperiodcentered}s{\textendash}1. A combustion progress pathway diagram was developed that describes the stages of smoldering and flaming combustion of a single dry biomass particle. An analysis of combustion kinetic parameters (activation energy and pre-exponential factor) and an energy balance analysis were also conducted to understand the differences between smoldering and flaming combustion.

}, doi = {10.1021/acs.energyfuels.6b00314}, url = {http://pubs.acs.org/doi/abs/10.1021/acs.energyfuels.6b00314}, author = {Wang, Houzhi and van Eyck, P. J. and Medwell, P. R. and Birzer, C. H. and Tian, Z. F. and Malcolm Possell} } @article {bnh-3431, title = {Emissions from prescribed fires in temperate forest in south-east Australia: implications for carbon accounting}, journal = {Biogeosciences}, volume = {12}, year = {2015}, month = {01/2015}, abstract = {

We estimated emissions of carbon, as equivalent CO2 (CO2e), from planned fires in four sites in a south-eastern Australian forest. Emission estimates were calculated using measurements of fuel load and carbon content of different fuel types, before and after burning, and determination of fuel-specific emission factors. Median estimates of emissions for the four sites ranged from 20 to 139 Mg CO2e ha-1. Variability in estimates was a consequence of different burning efficiencies of each fuel type from the four sites. Higher emissions resulted from more fine fuel (twigs, decomposing matter, near-surface live and leaf litter) or coarse woody debris (CWD; \> 25 mm diameter) being consumed. In order to assess the effect of declining information quantity and the inclusion of coarse woody debris when estimating emissions, Monte Carlo simulations were used to create seven scenarios where input parameters values were replaced by probability density functions. Calculation methods were (1) all measured data were constrained between measured maximum and minimum values for each variable; (2) as in (1) except the proportion of carbon within a fuel type was constrained between 0 and 1; (3) as in (2) but losses of mass caused by fire were replaced with burning efficiency factors constrained between 0 and 1; and (4) emissions were calculated using default values in the Australian National Greenhouse Accounts (NGA), National Inventory Report 2011, as appropriate for our sites. Effects of including CWD in calculations were assessed for calculation Method 1, 2 and 3 but not for Method 4 as the NGA does not consider this fuel type. Simulations demonstrate that the probability of estimating true median emissions declines strongly as the amount of information available declines. Including CWD in scenarios increased uncertainty in calculations because CWD is the most variable contributor to fuel load. Inclusion of CWD in scenarios generally increased the amount of carbon lost. We discuss implications of these simulations and how emissions from prescribed burns in temperate Australian forests could be improved.

}, doi = {10.5194/bg-12-257-2015}, url = {http://www.biogeosciences.net/12/257/2015/bg-12-257-2015-discussion.html}, author = {Malcolm Possell and Jenkins, Meaghan E. and Bell, Tina and Adams, Mark A.} } @article {bnh-2399, title = {Optimisation of fuel reduction burning regimes for fuel reduction, carbon, water and vegetation outcomes}, year = {2015}, author = {Malcolm Possell} }