& Key message Fire activity has decreased in the last decades in Spain as a whole and in most pro... more & Key message Fire activity has decreased in the last decades in Spain as a whole and in most provinces. However, fire risk factors have increased. Wildfires are burning preferentially treeless areas. Flammable pine areas burn less, while the less flammable oak forests burn more. This decreasing fire activity coincides with increasing fire suppression resources. & Context Climate and other fire risk factors are changing across the world, including the Mediterranean region. It is important to determine how fire activity is responding to such changes. & Aims To identify spatio-temporal changes in fire frequency and size, main tree species burned, and their association with changes in climate, land-use and land-cover, and fire suppression. & Methods Analysis of trends, breakpoints, and association among the time series of fire variables and fire risk factors during 1980-2013 in Spain at country and provincial levels. & Results Wildfires in Spain have been decreasing in number, burned area, mean, and largest fire sizes. Fires are more frequently burning treeless areas than forests. Pine forests are burning less, while oak forests are burning more. Fire suppression resources, particularly aerial ones, increased significantly. Risk factors like the mean summer fire weather index, and the forested and the artificial areas all increased. & Conclusion Despite increasing fire risk factors, wildfires have decreased at the country as a whole and in most provinces in Spain during the last 34 years.
Plant trait information is essential for understanding plant evolution, vegetation dynamics, and ... more Plant trait information is essential for understanding plant evolution, vegetation dynamics, and vegetation responses to disturbance and management. Furthermore, in Mediterranean ecosystems, changes in fire regime may be more relevant than direct changes in climatic conditions, making the knowledge of fire‐related traits especially important. Thus the purpose of this data set was to compile the most updated and comprehensive information on fire‐related traits for vascular plant species of the Mediterranean Basin, that is, traits related to plant persistence and regeneration after fire. Data were collected from an extensive literature review and from field and experimental observations. The data source is documented for each value. Since life history traits may vary spatially or with environmental conditions, we did not aggregate them by species; i.e., traits and species are repeated in different records if they were observed by different researchers and/or in different locations. Li...
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
During the last decades, climate and land use changes led to an increased prevalence of megafires... more During the last decades, climate and land use changes led to an increased prevalence of megafires in Mediterranean-type climate regions (MCRs). Here, we argue that current wildfire management policies in MCRs are destined to fail. Focused on fire suppression, these policies largely ignore ongoing climate warming and landscape-scale buildup of fuels. The result is a ‘firefighting trap’ that contributes to ongoing fuel accumulation precluding suppression under extreme fire weather, and resulting in more severe and larger fires. We believe that a ‘business as usual’ approach to wildfire in MCRs will not solve the fire problem, and recommend that policy and expenditures be rebalanced between suppression and mitigation of the negative impacts of fire. This requires a paradigm shift: policy effectiveness should not be primarily measured as a function of area burned (as it usually is), but rather as a function of avoided socio-ecological damage and loss.
Annual Land Use and Land Cover (LULC) maps are needed to identify the interaction between landsca... more Annual Land Use and Land Cover (LULC) maps are needed to identify the interaction between landscape changes and wildland fires. Objectives: In this work, we determined fire hazard changes in a representative Mediterranean landscape through the classification of annual LULC types and fire perimeters, using a dense Landsat Time Series (LTS) during the 1984–2017 period, and MODIS images. Methods: We implemented a semiautomatic process in the Google Earth Engine (GEE) platform to generate annual imagery free of clouds, cloud shadows, and gaps. We compared LandTrendr (LT) and FormaTrend (FT) algorithms that are widely used in LTS analysis to extract the pixel tendencies and, consequently, assess LULC changes and disturbances such as forest fires. These algorithms allowed us to generate the following change metrics: type, magnitude, direction, and duration of change, as well as the prechange spectral values. Results and conclusions: Our results showed that the FT algorithm was better than...
During the last decades, wildfires have been changing in many areas across the world, due to chan... more During the last decades, wildfires have been changing in many areas across the world, due to changes in climate, landscapes and socioeconomic drivers. However, how the role of these drivers changed over time has been little explored. Here, we assessed, in a spatially and temporally explicit way, the changing role of biophysical and human-related factors on wildfires in a rural area in west-central Spain from 1979 to 2008. Longitudinal Negative Binomial (NB) and Zero-Inflated Negative Binomial (ZINB) mixed models, with time as interacting factor (continuous and categorical), were used to model the number of fires of increasing size (≥1–10 ha, >10–100 ha, >100 ha) per 10 × 10 km cell per year, based on fire statistics. We found that the landscape was rather dynamic, and generally became more hazardous over time. Small fires increased and spread over the landscape with time, with medium and large fires being stable or decreasing. NB models were best for modelling small fires, whi...
The use of spatially explicit fire spread models to assess fire propagation and behaviour has sev... more The use of spatially explicit fire spread models to assess fire propagation and behaviour has several applications for fire management and research. We used the FARSITE simulator to predict the spread of a set of wildfires that occurred along an east–west gradient of the Euro-Mediterranean countries. The main purpose of this work was to evaluate the overall accuracy of the simulator and to quantify the effects of standard vs custom fuel models on fire simulation performance. We also analysed the effects of different fuel models and slope classes on the accuracy of FARSITE predictions. To run the simulations, several input layers describing each study area were acquired, and their effect on simulation outputs was analysed. Site-specific fuel models and canopy inputs were derived either from existing vegetation information and field sampling or through remote-sensing data. The custom fuel models produced an increase in simulation accuracy, and results were nearly unequivocal for all t...
Global warming is projected to increase the frequency and intensity of droughts in the Mediterran... more Global warming is projected to increase the frequency and intensity of droughts in the Mediterranean region, as well as the occurrence of large fires. Understanding the interactions between drought, fire and plant responses is therefore important. In this study, we present an experiment in which rainfall patterns were modified to simulate various levels of drought in a Mediterranean shrubland of central Spain dominated by Cistus ladanifer, Erica arborea and Phillyrea angustifolia. A system composed of automatic rainout shelters with an irrigation facility was used. It was designed to be applied in vegetation 2 m tall, treat relatively large areas (36 m 2), and be quickly dismantled to perform experimental burning and reassembled back again. Twenty plots were subjected to four rainfall treatments from early spring: natural rainfall, long-term average rainfall (2 months drought), moderate drought (25% reduction from long-term rainfall, 5 months drought) and severe drought (45% reduction, 7 months drought). The plots were burned in late summer, without interfering with rainfall manipulations. Results indicated that rainfall manipulations caused differences in soil moisture among treatments, leading to reduced water availability and growth of C. ladanifer and E. arborea in the drought treatments. However, P. angustifolia was not affected by the manipulations. Rainout shelters had a negligible impact on plot microenvironment. Experimental burns were of high fire intensity, without differences among treatments. Our system provides a tool to study the combined effects of drought and fire on vegetation, which is important to assess the threats posed by climate change in Mediterranean environments.
Predicted changes in the seasonality and amount of rainfall under a changing climate have the pot... more Predicted changes in the seasonality and amount of rainfall under a changing climate have the potential to dramatically alter ecosystem function and species composition. Moreover, in fire-prone ecosystems, the joint effects of fire and increasing aridity may create irreversible changes to the services these ecosystems provide. To understand the effects of increasing drought and fire in a Mediterranean shrubland, we
Understanding fire occurrence and its relationship with ignition sources and weather conditions i... more Understanding fire occurrence and its relationship with ignition sources and weather conditions is a major environmental challenge in regions affected by fire, particularly under ongoing and projected future climate change. The objectives of this study were: 1) To address a historical reconstruction of fire regime (fire occurrence, area burned, and fire causes) in Peninsular Spain for the last three decades. 2) Analyze the time x space relationship between fire occurrence and area burned with climatic variables and climate-derived fire danger indices. 3) Assess how climate change would affect fire danger indices for various emission scenarios based on projections of five regional climate models. The country was divided into 50x50 km cells, for which fire statistics were available. Climate data were interpolated at this grid so that daily fire danger indices were calculated for present and future conditions. Results showed an overall increase of fire occurrence and area burned over the past decades. Fire activity (number of fires and area burned) showed significant correlations with fire danger indices and climatic variables; although in some areas the relationship was weak given the uncertainty linked to the number of ignitions caused by people. There was a significant correlation between certain fire indices and Gini coefficient of fire sizes, whereby fires under more severe conditions become more variable in size. Towards the end of this century (2071-2100) increases in the fire danger indices, and a longer period of fire danger are projected. This trend is consistent among models.
& Key message Fire activity has decreased in the last decades in Spain as a whole and in most pro... more & Key message Fire activity has decreased in the last decades in Spain as a whole and in most provinces. However, fire risk factors have increased. Wildfires are burning preferentially treeless areas. Flammable pine areas burn less, while the less flammable oak forests burn more. This decreasing fire activity coincides with increasing fire suppression resources. & Context Climate and other fire risk factors are changing across the world, including the Mediterranean region. It is important to determine how fire activity is responding to such changes. & Aims To identify spatio-temporal changes in fire frequency and size, main tree species burned, and their association with changes in climate, land-use and land-cover, and fire suppression. & Methods Analysis of trends, breakpoints, and association among the time series of fire variables and fire risk factors during 1980-2013 in Spain at country and provincial levels. & Results Wildfires in Spain have been decreasing in number, burned area, mean, and largest fire sizes. Fires are more frequently burning treeless areas than forests. Pine forests are burning less, while oak forests are burning more. Fire suppression resources, particularly aerial ones, increased significantly. Risk factors like the mean summer fire weather index, and the forested and the artificial areas all increased. & Conclusion Despite increasing fire risk factors, wildfires have decreased at the country as a whole and in most provinces in Spain during the last 34 years.
Plant trait information is essential for understanding plant evolution, vegetation dynamics, and ... more Plant trait information is essential for understanding plant evolution, vegetation dynamics, and vegetation responses to disturbance and management. Furthermore, in Mediterranean ecosystems, changes in fire regime may be more relevant than direct changes in climatic conditions, making the knowledge of fire‐related traits especially important. Thus the purpose of this data set was to compile the most updated and comprehensive information on fire‐related traits for vascular plant species of the Mediterranean Basin, that is, traits related to plant persistence and regeneration after fire. Data were collected from an extensive literature review and from field and experimental observations. The data source is documented for each value. Since life history traits may vary spatially or with environmental conditions, we did not aggregate them by species; i.e., traits and species are repeated in different records if they were observed by different researchers and/or in different locations. Li...
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
During the last decades, climate and land use changes led to an increased prevalence of megafires... more During the last decades, climate and land use changes led to an increased prevalence of megafires in Mediterranean-type climate regions (MCRs). Here, we argue that current wildfire management policies in MCRs are destined to fail. Focused on fire suppression, these policies largely ignore ongoing climate warming and landscape-scale buildup of fuels. The result is a ‘firefighting trap’ that contributes to ongoing fuel accumulation precluding suppression under extreme fire weather, and resulting in more severe and larger fires. We believe that a ‘business as usual’ approach to wildfire in MCRs will not solve the fire problem, and recommend that policy and expenditures be rebalanced between suppression and mitigation of the negative impacts of fire. This requires a paradigm shift: policy effectiveness should not be primarily measured as a function of area burned (as it usually is), but rather as a function of avoided socio-ecological damage and loss.
Annual Land Use and Land Cover (LULC) maps are needed to identify the interaction between landsca... more Annual Land Use and Land Cover (LULC) maps are needed to identify the interaction between landscape changes and wildland fires. Objectives: In this work, we determined fire hazard changes in a representative Mediterranean landscape through the classification of annual LULC types and fire perimeters, using a dense Landsat Time Series (LTS) during the 1984–2017 period, and MODIS images. Methods: We implemented a semiautomatic process in the Google Earth Engine (GEE) platform to generate annual imagery free of clouds, cloud shadows, and gaps. We compared LandTrendr (LT) and FormaTrend (FT) algorithms that are widely used in LTS analysis to extract the pixel tendencies and, consequently, assess LULC changes and disturbances such as forest fires. These algorithms allowed us to generate the following change metrics: type, magnitude, direction, and duration of change, as well as the prechange spectral values. Results and conclusions: Our results showed that the FT algorithm was better than...
During the last decades, wildfires have been changing in many areas across the world, due to chan... more During the last decades, wildfires have been changing in many areas across the world, due to changes in climate, landscapes and socioeconomic drivers. However, how the role of these drivers changed over time has been little explored. Here, we assessed, in a spatially and temporally explicit way, the changing role of biophysical and human-related factors on wildfires in a rural area in west-central Spain from 1979 to 2008. Longitudinal Negative Binomial (NB) and Zero-Inflated Negative Binomial (ZINB) mixed models, with time as interacting factor (continuous and categorical), were used to model the number of fires of increasing size (≥1–10 ha, >10–100 ha, >100 ha) per 10 × 10 km cell per year, based on fire statistics. We found that the landscape was rather dynamic, and generally became more hazardous over time. Small fires increased and spread over the landscape with time, with medium and large fires being stable or decreasing. NB models were best for modelling small fires, whi...
The use of spatially explicit fire spread models to assess fire propagation and behaviour has sev... more The use of spatially explicit fire spread models to assess fire propagation and behaviour has several applications for fire management and research. We used the FARSITE simulator to predict the spread of a set of wildfires that occurred along an east–west gradient of the Euro-Mediterranean countries. The main purpose of this work was to evaluate the overall accuracy of the simulator and to quantify the effects of standard vs custom fuel models on fire simulation performance. We also analysed the effects of different fuel models and slope classes on the accuracy of FARSITE predictions. To run the simulations, several input layers describing each study area were acquired, and their effect on simulation outputs was analysed. Site-specific fuel models and canopy inputs were derived either from existing vegetation information and field sampling or through remote-sensing data. The custom fuel models produced an increase in simulation accuracy, and results were nearly unequivocal for all t...
Global warming is projected to increase the frequency and intensity of droughts in the Mediterran... more Global warming is projected to increase the frequency and intensity of droughts in the Mediterranean region, as well as the occurrence of large fires. Understanding the interactions between drought, fire and plant responses is therefore important. In this study, we present an experiment in which rainfall patterns were modified to simulate various levels of drought in a Mediterranean shrubland of central Spain dominated by Cistus ladanifer, Erica arborea and Phillyrea angustifolia. A system composed of automatic rainout shelters with an irrigation facility was used. It was designed to be applied in vegetation 2 m tall, treat relatively large areas (36 m 2), and be quickly dismantled to perform experimental burning and reassembled back again. Twenty plots were subjected to four rainfall treatments from early spring: natural rainfall, long-term average rainfall (2 months drought), moderate drought (25% reduction from long-term rainfall, 5 months drought) and severe drought (45% reduction, 7 months drought). The plots were burned in late summer, without interfering with rainfall manipulations. Results indicated that rainfall manipulations caused differences in soil moisture among treatments, leading to reduced water availability and growth of C. ladanifer and E. arborea in the drought treatments. However, P. angustifolia was not affected by the manipulations. Rainout shelters had a negligible impact on plot microenvironment. Experimental burns were of high fire intensity, without differences among treatments. Our system provides a tool to study the combined effects of drought and fire on vegetation, which is important to assess the threats posed by climate change in Mediterranean environments.
Predicted changes in the seasonality and amount of rainfall under a changing climate have the pot... more Predicted changes in the seasonality and amount of rainfall under a changing climate have the potential to dramatically alter ecosystem function and species composition. Moreover, in fire-prone ecosystems, the joint effects of fire and increasing aridity may create irreversible changes to the services these ecosystems provide. To understand the effects of increasing drought and fire in a Mediterranean shrubland, we
Understanding fire occurrence and its relationship with ignition sources and weather conditions i... more Understanding fire occurrence and its relationship with ignition sources and weather conditions is a major environmental challenge in regions affected by fire, particularly under ongoing and projected future climate change. The objectives of this study were: 1) To address a historical reconstruction of fire regime (fire occurrence, area burned, and fire causes) in Peninsular Spain for the last three decades. 2) Analyze the time x space relationship between fire occurrence and area burned with climatic variables and climate-derived fire danger indices. 3) Assess how climate change would affect fire danger indices for various emission scenarios based on projections of five regional climate models. The country was divided into 50x50 km cells, for which fire statistics were available. Climate data were interpolated at this grid so that daily fire danger indices were calculated for present and future conditions. Results showed an overall increase of fire occurrence and area burned over the past decades. Fire activity (number of fires and area burned) showed significant correlations with fire danger indices and climatic variables; although in some areas the relationship was weak given the uncertainty linked to the number of ignitions caused by people. There was a significant correlation between certain fire indices and Gini coefficient of fire sizes, whereby fires under more severe conditions become more variable in size. Towards the end of this century (2071-2100) increases in the fire danger indices, and a longer period of fire danger are projected. This trend is consistent among models.
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