Recent Trends in Fire Regimes and Associated Territorial Features in a Fire-Prone Mediterranean Region

Abstract

Fire regimes in Mediterranean countries have been shifting in recent decades, including changes in wildfire size and frequency. We sought to describe changes in fire regimes across two periods (1975–1995 and 1996–2018) in a fire-prone region of central Portugal, explore the relationships between these regimes and territorial features, and check whether these associations persisted across periods. Two independent indicators of fire regimes were determined at parish level: fire incidence and burn concentration. Most parishes presented higher values of both indicators in the second period. Higher values of fire incidence were associated with lower population densities, lower proportions of farmland areas and higher proportions of natural vegetation. Higher levels of burn concentration were associated with smaller areas of farmland and natural vegetation. These associations differed across periods, reflecting contrasting climatic and socio-economic contexts. Keeping 40% of a parish territory covered by farmland was effective to buffer the increased wildfire risks associated with different management and climate contexts. The effectiveness of higher population densities in keeping fire incidence low decreased in the last decades. The results can improve the knowledge on the temporal evolution of fire regimes and their conditioning factors, providing contributions for spatial planning and forest/wildfire management policies.

Promoting Low-Risk Fire Regimes: An Agent-Based Model to Explore Wildfire Mitigation Policy Options

“…However, it should be noted that much European forest, especially in the south, is currently man-made, sometimes including exotic species such as eucalypt rather than natural forests [59]. In Mediterranean climate regions such as the study area, the high prevalence of monocultural forest plantations in the landscape and its excessive spatial concentration substantially increase the risk of mega-wildfires [7,19] which, among many other negative impacts, are also responsible for releasing high amounts of organic carbon into the atmosphere.…”

“…Fire regimes are used to depict combinations of fire frequency and severity [15,17,18]. Fire regimes are often characterized based on metrics such as total burn area, number of fire events, or spatiotemporal concentration indexes (e.g., Gini index), computed over a representative period of time [15,17,19]. Climate, topography, and LUC are acknowledged drivers of fire regimes [18,20].…”

Estimating the Trade-Offs between Wildfires and Carbon Stocks across Landscape Types to Inform Nature-Based Solutions in Mediterranean Regions

“…Landscape specialization, in Portugal and other Mediterranean countries, is characterized by agricultural intensification on fertile lands and farmland retreat on marginal lands, where forests have regenerated or were installed, often with fast growing species in large patches, increasing fuel continuity and fire risks [6,10,21]. Nowadays, agricultural and forest plantations have created large scale specialized landscapes, while the rest of the territory is abandoned where no viable socioecological solution is possible [22].…”

“…Actually, some studies point to a strong association of extreme wildfire events with some LULC types [3,[40][41][42][43], while others attributed LULC a minor influence on fire severity and size [44,45]. A wider region on central Portugal was recently studied focusing on landscape level (represented by parishes), and the authors found an expressive association of LULC with FRs, but even in these cases there was a limited number and range of landscape types [21,30,46]. In another recent study for all mainland Portugal assessing twelve FR drivers, the role of land-cover was variable, depending on FRs, but very influential in extremely hazardous regimes [16].…”

“…In this study FR is following sensu stricto concept from [47] including only temporal and spatial distribution to determine fire characteristics. FR characteristics on our modelling setup were cumulative percentage of burned area (CPBA) over a 36 year period , and a temporal concentration index in such burned area at the landscape level, assessed through the Gini Concentration Index (GCI), following other studies [21,46], but integrating both variables to establish meaningful FR categories [30] at the landscape level.…”