The Importance of Vegetation Build Up for Burnt Area Seasonality

2020 ◽  
Author(s):  
Alexander Kuhn-Regnier ◽  
Apostolos Voulgarakis ◽  
Sandy Harrison ◽  
Colin Prentice
Keyword(s):  
Cloud Cover ◽  
Management Practices ◽  
Fire Regimes ◽  
Exact Nature ◽  
Contributing Factors ◽  
Burnt Area ◽  
Vegetation Productivity ◽  
Fire Models ◽  
In Fire ◽  
The Relationship

<p>Vegetation build up is a major controlling factor for wildfires globally. The exact nature of the dependency of wildfire activity on past vegetation productivity is still under debate, however. Given the potential future rise in conditions conducive to extremely damaging fires in many regions of the world, controlling factors like this need to be investigated urgently to better understand and manage especially extreme wildfire events.<br>To improve our understanding of wildfires and the advice given to policy makers, a comprehensive understanding of all contributing factors is required. Changes to land management can be controversial and thus concrete evidence is required to assess and modify longstanding management practices and regulations if needed.<br>We therefore used global satellite datasets extending from 2005 to 2011 to assess the relationship between burnt area and various biophysical variables. Vegetation proxy data included vegetation optical depth and the fraction of absorbed photosynthetically activate radiation. Different regions and time periods were analysed separately to isolate regional and temporal effects respectively. The relationship between pre-season vegetation productivity and burnt area was modelled as a regionally and temporally varying weighted sum of past monthly productivity proxies.<br>As expected, significant differences in fire regimes were found across biomes, signified for example by significant shifts in the seasonality of burnt area. Understanding these shifts in the seasonality of both burnt area and the accompanying temporal dependence on past vegetation growth is key to reproducing observed wildfire regimes in fire models. As these relationships were found to vary both temporally and regionally, judicious inclusion of biophysical variables in fire models coupled with algorithms able to capture these relationships is necessary. <br>However, remotely sensed observations were of different quality in different areas due to inhomogeneous cloud cover patterns, making assessments for much-affected regions like South America and South East Asia especially difficult. Likewise, the found correlation between decreasing cloud cover and increasing burnt area biased our results. Due also to the short time span of the data available in this investigation, these factors warrant further investigation to more fully quantify the temporal and regional relationships at work.</p>

scholarly journals Reconstructing burnt area during the Holocene: an Iberian case study

2021 ◽  
Author(s):  
Yicheng Shen ◽  
Luke Sweeney ◽  
Mengmeng Liu ◽  
Jose Antonio Lopez Saez ◽  
Sebastián Pérez-Díaz ◽  
...  
Keyword(s):  
Fire Regimes ◽  
Weighted Averaging ◽  
Pollen Data ◽  
Burnt Area ◽  
The Holocene ◽  
Quantitative Estimates ◽  
In Fire ◽  
The Impact ◽  
Pollen Records

Abstract. Charcoal accumulated in lake, bog or other anoxic sediments through time has been used to document the geographical patterns in changes in fire regimes. Such reconstructions are useful to explore the impact of climate and vegetation changes on fire during periods when the human influence was less prevalent than today. However, charcoal records only provide semi-quantitative estimates of change in biomass burning. Here we derive quantitative estimates of burnt area from vegetation data in two stages. First, we relate the modern charcoal abundance to burnt area using a conversion factor derived from a generalized linear model of burnt area probability based on eight environmental predictors. Then, we establish the relationship between fossil pollen assemblages and burnt area using Tolerance-weighted Weighted Averaging Partial Least-Squares with sampling frequency correction (fxTWA-PLS). We test this approach using the Iberian Peninsula as a case study because it is a fire-prone region with abundant pollen and charcoal records covering the Holocene. We derive the vegetation-burnt area relationship using the 29 records that have both modern and fossil charcoal and pollen data, and then reconstruct palaeo-burnt area for the 114 records with Holocene pollen records. The pollen data predict charcoal abundances through time relatively well (R2 = 0.47) and the changes in reconstructed burnt area are synchronous with known climate changes through the Holocene. This new method opens up the possibility of reconstructing changes in fire regimes quantitatively from pollen records, which are far more numerous than charcoal records.

scholarly journals Academic Achievement: It Is Not How Smart You Are, But How You Cope With Your Life And Manage Your Time

2015 ◽  
Vol 8 (2) ◽  
pp. 1535-1547
Author(s):  
Azura Hamdan ◽  
Rohany Nasir ◽  
Rozainee Khairudin ◽  
Wan Shahrazad Wan Sulaiman
Keyword(s):  
Academic Achievement ◽  
Grade Point Average ◽  
Undergraduate Students ◽  
Time Management ◽  
Management Practices ◽  
Contributing Factors ◽  
Grade Point ◽  
High School Grades ◽  
Academic Grades ◽  
The Relationship

Previous research suggests that contributing factors such as previous academic result, coping and time management can predict student success at the universities.  The purpose of this study was to investigate the relationship between previous academic grades, coping and time management practices on academic achievement among undergraduate students from four of Malaysia public institutions for higher education. 551 university students completed a Time Management Questionnaire (TMQ), COPE Inventory and provided their self-reported high school grades and current Grade Point Average (GPA).  Analysis of data from descriptive and inferential statistics was done.  Results showed that previous academic grades and the practice of time management (short range planning and attitude toward time) have no direct effect on academic achievement.  However, the use of coping strategies (problem focused and denial focused) and the practice of time management (long range planning) showed that there was a significant effect on Grade Point Average (GPA).

scholarly journals Quantitative assessment of fire and vegetation properties in simulations with fire-enabled vegetation models from the Fire Model Intercomparison Project

2020 ◽  
Vol 13 (7) ◽  
pp. 3299-3318 ◽  
Author(s):  
Stijn Hantson ◽  
Douglas I. Kelley ◽  
Almut Arneth ◽  
Sandy P. Harrison ◽  
Sally Archibald ◽  
...  
Keyword(s):  
Environmental Change ◽  
Spatial Pattern ◽  
Fire Regimes ◽  
Model Intercomparison ◽  
Burnt Area ◽  
Fire Model ◽  
Fire Models ◽  
Observational Uncertainty ◽  
Intercomparison Project ◽  
Vegetation Models

Abstract. Global fire-vegetation models are widely used to assess impacts of environmental change on fire regimes and the carbon cycle and to infer relationships between climate, land use and fire. However, differences in model structure and parameterizations, in both the vegetation and fire components of these models, could influence overall model performance, and to date there has been limited evaluation of how well different models represent various aspects of fire regimes. The Fire Model Intercomparison Project (FireMIP) is coordinating the evaluation of state-of-the-art global fire models, in order to improve projections of fire characteristics and fire impacts on ecosystems and human societies in the context of global environmental change. Here we perform a systematic evaluation of historical simulations made by nine FireMIP models to quantify their ability to reproduce a range of fire and vegetation benchmarks. The FireMIP models simulate a wide range in global annual total burnt area (39–536 Mha) and global annual fire carbon emission (0.91–4.75 Pg C yr−1) for modern conditions (2002–2012), but most of the range in burnt area is within observational uncertainty (345–468 Mha). Benchmarking scores indicate that seven out of nine FireMIP models are able to represent the spatial pattern in burnt area. The models also reproduce the seasonality in burnt area reasonably well but struggle to simulate fire season length and are largely unable to represent interannual variations in burnt area. However, models that represent cropland fires see improved simulation of fire seasonality in the Northern Hemisphere. The three FireMIP models which explicitly simulate individual fires are able to reproduce the spatial pattern in number of fires, but fire sizes are too small in key regions, and this results in an underestimation of burnt area. The correct representation of spatial and seasonal patterns in vegetation appears to correlate with a better representation of burnt area. The two older fire models included in the FireMIP ensemble (LPJ–GUESS–GlobFIRM, MC2) clearly perform less well globally than other models, but it is difficult to distinguish between the remaining ensemble members; some of these models are better at representing certain aspects of the fire regime; none clearly outperforms all other models across the full range of variables assessed.

scholarly journals Sensitivity of simulated historical burned area to environmental andanthropogenic controls: A comparison of seven fire models

2019 ◽  
Author(s):  
Lina Teckentrup ◽  
Sandy P. Harrison ◽  
Stijn Hantson ◽  
Angelika Heil ◽  
Joe R. Melton ◽  
...  
Keyword(s):  
Land Use ◽  
Global Change ◽  
Fire Regime ◽  
Fire Behavior ◽  
Fire Regimes ◽  
Burned Area ◽  
Strong Response ◽  
Fire Models ◽  
In Fire ◽  
The Impact

Abstract. Understanding how fire regimes change over time is of major importance for understanding their future impact on the Earth system, including society. Large differences in simulated burned area between fire models show that there is substantial uncertainty associated with modelling global change impacts on fire regimes. We draw here on sensitivity simulations made by seven global dynamic vegetation models participating in the Fire Model Intercomparison Project (FireMIP) to understand how differences in models translate into differences in fire regime projections. The sensitivity experiments isolate the impact of the individual drivers of fire, which are prescribed in the simulations. Specifically these drivers are atmospheric CO2, population density, land-use change, lightning and climate. The seven models capture spatial patterns in burned area. However, they show considerable differences in the burned area trends since 1900. We analyse the trajectories of differences between the sensitivity and reference simulation to improve our understanding of what drives the global trend in burned area. Where it is possible, we link the inter-model differences to model assumptions. Overall, these analyses reveal that the strongest differences leading to diverging trajectories are related to the way anthropogenic ignitions and suppression, as well as the effects of land-use on vegetation and fire, are incorporated in individual models. This points to a need to improve our understanding and model representation of the relationship between human activities and fire to improve our abilities to model fire for global change applications. Only two models show a strong response to CO2 and the response to lightning on global scale is low for all models. The sensitivity to climate shows a spatially heterogeneous response and globally only two models show a significant trend. It was not possible to attribute the climate-induced changes in burned area to model assumptions or specific climatic parameters. However, the strong influence of climate on the inter-annual variability in burned area, shown by all the models, shows that we need to pay attention to the simulation of fire weather but also meteorological influences on biomass accumulation and fuel properties in order to better capture extremes in fire behavior.

scholarly journals Testing Vegetation Flammability: The Problem of Extremely Low Ignition Frequency and Overall Flammability Score

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Zorica Kauf ◽  
Andreas Fangmeier ◽  
Roman Rosavec ◽  
Željko Španjol
Keyword(s):  
Leaf Litter ◽  
Management Practices ◽  
Fire Regime ◽  
Fire Regimes ◽  
Testing Methods ◽  
Testing Conditions ◽  
Similar Materials ◽  
Measured Information ◽  
In Fire ◽  
Extreme Fire

In the recent decades changes in fire regimes led to higher vulnerability of fire prone ecosystems, with vegetation being the only component influencing fire regime which can be managed in order to reduce probability of extreme fire events. For these management practices to be effective reliable information on the vegetation flammability is being crucial. Epiradiator based testing methods are one of the methods commonly used to investigate vegetation flammability and decrease in ignition frequency is always interpreted as a decrease in flammability. Furthermore, gathered information is often combined into a single flammability score. Here we present results of leaf litter testing which, together with previously conducted research on similar materials, show that material with very low ignition frequency under certain testing conditions can be extremely flammable if testing conditions are slightly changed. Additionally, our results indicate that combining measured information into one single flammability score, even though sometimes useful, is not always meaningful and should be performed with caution.

scholarly journals Understanding and modelling wildfire regimes: an ecological perspective

2021 ◽  
Author(s):  
Sandy P Harrison ◽  
Iain Colin Prentice ◽  
Keith J Bloomfield ◽  
Ning Dong ◽  
Matthias Forkel ◽  
...  
Keyword(s):  
Fire Ecology ◽  
Forest Cover ◽  
Plant Traits ◽  
Fire Suppression ◽  
Fire Regimes ◽  
Burnt Area ◽  
Dry Conditions ◽  
In Fire ◽  
The Impact ◽  
Wildfire Regimes

Abstract Recent extreme wildfire seasons in several regions have been associated with exceptionally hot, dry conditions, made more probable by climate change. Much research has focused on extreme fire weather and its drivers, but natural wildfire regimes – and their interactions with human activities – are far from being comprehensively understood. There is a lack of clarity about the ‘causes’ of wildfire, and about how ecosystems could be managed for the co-existence of wildfire and people. We present evidence supporting an ecosystem-centred framework for improved understanding and modelling of wildfire. Wildfire has a long geological history and is a pervasive natural process in contemporary plant communities. In some biomes, wildfire would be more frequent without human settlement; in others they would be unchanged or less frequent. A world without fire would have greater forest cover, especially in present-day savannas. Many species would be missing, because fire regimes have co-evolved with plant traits that resist, adapt to or promote wildfire. Certain plant traits are favoured by different fire frequencies, and may be missing in ecosystems that are normally fire-free. For example, post-fire resprouting is more common among woody plants in high-frequency fire regimes than where fire is infrequent. The impact of habitat fragmentation on wildfire crucially depends on whether the ecosystem is fire-adapted. In normally fire-free ecosystems, fragmentation facilitates wildfire starts and is detrimental to biodiversity. In fire-adapted ecosystems, fragmentation inhibits fires from spreading and fire suppression is detrimental to biodiversity. This interpretation explains observed, counterintuitive patterns of spatial correlation between wildfire and potential ignition sources. Lightning correlates positively with burnt area only in open ecosystems with frequent fire. Human population correlates positively with burnt area only in densely forested regions. Models for vegetation-fire interactions must be informed by insights from fire ecology to make credible future projections in a changing climate.

Reconstructing Holocene vegetation-fire regimes in the Iberian Peninsula

2021 ◽  
Author(s):  
Yicheng Shen ◽  
Sandy Harrison ◽  
Colin Prentice
Keyword(s):  
Iberian Peninsula ◽  
Predictive Power ◽  
Quantitative Relationship ◽  
Fire Regimes ◽  
Weighted Averaging ◽  
Sources Of Information ◽  
Pollen Data ◽  
Burnt Area ◽  
Pollen Taxon ◽  
In Fire

<p>Analyses of the regional controls representing climate, vegetation and human activities on modern burnt area in the Iberian Peninsula show that the vegetation properties that determine fuel availability are major influences on the occurrence of fire. This finding opens up the possibility of using pollen data to reconstruct past changes in fire regimes. We could then make use of the much greater abundance of pollen data compared to other sources of information on past fire regimes to constrain biomass-burning feedbacks to the carbon cycle and climate. We applied Tolerance-Weighted Averaging Partial Least-Squares (TWA-PLS) to derive quantitative relationships between pollen-taxon and charcoal abundances from 15 entities from the Iberian Peninsula, using core-top charcoal data and a generalized linear model of present-day fire probability to provide conversion factors between the relative scale of charcoal abundance and the absolute scale of fire. We show that pollen taxon abundance has good predictive power for fire (r<sup>2</sup> = 0.56) and that the contribution of specific taxa to the prediction makes sense in terms of their ecological adaptations to fire. We apply the TWA-PLS quantitative relationship to predict changing fire regimes across the Iberian Peninsula through the Holocene. Results show that fire change synchronous with climate warming events.</p>

An overview of mountain meteorological effects relevant to fire behaviour and bushfire risk

2009 ◽  
Vol 18 (7) ◽  
pp. 737 ◽  
Author(s):  
Jason J. Sharples
Keyword(s):  
Management Practices ◽  
Complex Dynamics ◽  
Fire Regimes ◽  
Emergent Properties ◽  
Fire Weather ◽  
Fire Behaviour ◽  
Rugged Terrain ◽  
Wide Range ◽  
In Fire ◽  
Meteorological Effects

Many of the processes that can occur in mountainous landscapes have the potential to significantly affect fire behaviour and bushfire risk in general. These processes can lead to otherwise unexpected fire behaviour and escalation in fire size and severity that could endanger firefighting crews and compromise suppression activities. Interaction of upper winds with rugged terrain can often result in highly variable and turbulent wind patterns and variations in temperature and humidity that can affect fire regimes in the long and short term. More generally, the effect of rugged terrain on atmospheric flows can give rise to complex dynamics and emergent properties that are discontinuous in nature. Hence, the ‘fire weather continuum’ that is often assumed in fire management practices is of reduced validity in mountainous or hilly landscapes. This paper presents an overview of the main elements of mountain meteorology relevant to fire weather and discusses the potential roles they may play in bushfire behaviour, development and risk. As such, the paper is intended to promote understanding, across the wide range of professions concerned with bushfire, of how mountain meteorological effects might contribute to fire potential and fire behaviour.

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