Canadian Forest Service Publications
Climate change-induced shifts in fire for Mediterranean ecosystems. 2013. Batllori, E.; Parisien, M.-A.; Krawchuk, M.A.; Moritz, M.A. Global Ecology and Biogeography 22(10):1118-1129.
Issued by: Northern Forestry Centre
Catalog ID: 34800
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Aim: Pyrogeographical theory suggests that fire is controlled by spatial gradients in resources to burn (fuel amount) and climatic conditions promoting combustion(fuel moisture). Examining trade-offs among these environmental constraints is critical to understanding future fire activity. We evaluate constraints on fire frequency in modern fire records over the entire Mediterranean biome and identify potential shifts in fire activity under an ensemble of global climate projections.
Location: The biome encompassing the Mediterranean-type ecosystems (MTEs).
Methods: We evaluate potential changes in fire over the 21st century in MTEs based on a standardized global framework. Future fire predictions are generated from statistical fire-climate models driven by ensembles of climate projections under the IPCC A2 emissions scenario depicting warmer–drier and warmer–wetter syndromes. We test the hypothesis that MTEs lie in the transition zone discriminating fuel moisture versus fuel amount as the dominant constraint on fire activity.
Results: Fire increases reported in MTEs in recent decades may not continue throughout the century. MTEs occupy a sensitive portion of global fire-climate relationships, especially for precipitation-related variables, leading to highly divergent fire predictions under drier versus wetter syndromes. Warmer–drier conditions ould result in decreased fire activity over more than half the Mediterranean biome by 2070–2099, and the opposite is predicted under a warmer–wetter future. MTEs encompass, however, a climate space broad and complex enough to include spatially varied fire responses and potential conversions to non-MTE biomes.
Main conclusions: Our results strongly support the existence of both fuel amount and fuelmoisture constraints on fire activity and show their geographically variable influence throughout MTEs. Climatic controls on fire occurrence in MTEs lie close to ‘tipping points’, where relatively small changes in future climates could translate into drastic and divergent shifts in fire activity over the Mediterranean biome, mediated by productivity alterations.
Plain Language Summary
Global wildfire activity is strongly linked to climate, and as climate changes, so does the wildfire activity. A major concern in fire-prone parts of the world is that conditions that tend to favour wildfires—hot, dry, and windy weather (hereafter, “fire weather”)—are expected to increase in the future. This study focuses on the world’s five Mediterranean areas, which support vegetation ranging from fairly lush forests to dry shrublands. Using statistical models, we assessed the role of climate on wildfire in these areas and made some predictions of wildfire activity over the next century. The results showed that the response of wildfire to changes in climate within the Mediterranean areas is not straightforward. Where currently there is ample vegetation, future wildfire activity is generally predicted to increase. By contrast, in shrubland areas where vegetation is sparser, hotter and drier conditions will likely lead to a loss in vegetation cover, hence a reduction in potential wildfire. This publication shows that the extreme fire weather expected for the future may yield an increase in wildfire activity in some areas and a decrease in others.