Landscape variables influencing forest fires in central Spain

Abstract

In assessing fire risk, it is important to determine whether all areas in a landscape burn at similar rates. This goal is complicated by the limitations of burned-area data and the temporally dynamic nature of landscapes. We assessed the differential degree of forest-fire burning for six landscape variables (land-use–land-cover type, distances to roads and towns, topography (slope, aspect, elevation)), each comprising several categories. The study area (95 × 55 km) was located in central Spain, and the study period covered 16 years. Landsat multispectral scanner images were used to annually map fire perimeters and to classify the landscape. We calculated an annual resource selection index for each category within a variable. The sizes and shapes of all fires occurring within a year were randomly distributed into the landscape 1000 times, and the corresponding resource selection index was calculated. This provided a null random-burning model against which we tested the actual resource selection index of the fires in each year. Pine woodlands showed consistent and significant positive fire selectivity, whereas deciduous woodlands showed consistent and significant negative selectivity. No differences in the resource selection indices of land-use–land-cover types were found between large (>100 ha) and small fires (<100 ha). Fires positively selected (resource selection index >1) areas at small or intermediate distances to towns and intermediate distances to roads. Selectivity for topographic variables was less marked. Our study demonstrates that landscape variables defining composition (land-use–land-cover type) or proximity to human influence are important factors for fire risk.

Microclimate and Modeled Fire Behavior Differ Between Adjacent Forest Types in Northern Portugal

“…Modification of fire behavior characteristics is expected to disturb or disrupt landscape fire growth, directly, by delaying or impeding fire spread and, indirectly, by allowing successful fire suppression operations, hence, translating into less area burned and differential burning rates among vegetation types. Fire selects flammable conifer types over evergreen broadleaves [23], deciduous broadleaves [24,25], broadleaves in general [26][27][28], and short-needled conifers [26], although preferential burning is affected by stand structure [29] and decreases with fire size [23,30]. Those studies support the contention that decreasing fire hazard, either by treating fuels in flammable cover types or their conversion to less fire-prone vegetation types [1,2] should supplement fuel-break networks that often fail to halt fire spread [31].…”

Trends in adverse weather patterns and large wildland fires in Aragón (NE Spain) from 1978 to 2010

“…Large wildland fires (LWFs) are defined in this work as those over 100 ha threshold (Moreno et al, 2011;De Zea Bermudez et al, 2009). In order to understand the interactions between HTD and LWF in the study period in Aragón, we processed the historical fire data records from Spain's EGIF database (General Statistics on Wildland Fires; see www.magrama.gob.es, accessed last time on 30 October 2012), which includes the wildland fire reports sent to the Ministry of the Environment by the firefighting and forest management services of all the Spanish regions.…”

Land cover fire proneness in Europe

“…Fire selectivity has been studied for vegetation classes in terms of fire frequency and fire size in Canton Ticino, Switzerland (Pezzatti et al, 2009) and Portugal (Barros & Pereira, 2014), alone or integrated with other landscape variables such as topography (slope, aspect, elevation) and distance to roads and towns in central Spain (Moreno et al, 2011) and northern Portugal (Carmo et al, 2011), to test the sensitivity of the landscape to forest fires in peri-urban area of Athens, Greece, to land cover changes (Salvati & Ferrara, 2014) and to define landscape management guidelines and policies based on the relationships between landscape and fires in the Mediterranean region . These studies inspired the present work which aims to: (i) analyse the spatial and temporal variability of these statistics within the European countries; and, (ii) identify and characterize the land cover classes most affected by fires and consequently their fire proneness, devoting special attention to mixed forests.…”