Abstract
Human-caused wildfires are often regarded as unpredictable, but usually occur in patterns aggregated over space and time. We analysed the spatio-temporal configuration of 7790 anthropogenic wildfires (2007–2013) in nine study areas distributed throughout Peninsular Spain by using the Ripley’s K-function. We also related these aggregation patterns to weather, population density, and landscape structure descriptors of each study area. Our results provide statistical evidence for spatio-temporal structures around a maximum of 4 km and six months. These aggregations lose strength when the spatial and temporal distances increase. At short time lags after a wildfire (<1 month), the probability of another fire occurrence is high at any distance in the range of 0–16 km. When considering larger time lags (up to two years), the probability of fire occurrence is high only at short distances (>3 km). These aggregated patterns vary depending on location in Spain. Wildfires seem to aggregate within fewer days (heat waves) in warm and dry Mediterranean regions than in milder Atlantic areas (bimodal fire season). Wildfires aggregate spatially over shorter distances in diverse, fragmented landscapes with many small and complex patches. Urban interfaces seem to spatially concentrate fire occurrence, while wildland-agriculture interfaces correlate with larger aggregates.
Highlights
Human-caused fires (HCFs) do not occur randomly, they follow spatio-temporal patterns that change depending on the socioeconomic activity linked to the use or misuse of fire triggering ignitions [1]
Spatio-Temporal Aggregation of HCFs In Figure 5, we compare K (u, v) 2 u 2 v and tolerance envelopes suggesting the presence of In Figure 5, we compare Kst − 2πu2 v and tolerance envelopes suggesting the presence of different spatio-temporal spatio‐temporal structures structures for for time time lags lags of of less less than than two two years years and and ignition ignition point point distances distances different in the therange rangeofof0–16
Previous studies done in the Iberian Peninsula [43,50], found direct relations between population density and HCF occurrence; we found that higher population density causes distance-aggregation or spatially closer fires and dilates the time lag for wildfire occurrence, though the correlations were not very high
Summary
Human-caused fires (HCFs) do not occur randomly, they follow spatio-temporal patterns that change depending on the socioeconomic activity linked to the use or misuse of fire triggering ignitions [1]. The characterization of spatio-temporal patterns of fire ignition can provide important information for optimizing resource allocation in strategic firefighting [7]. Fire management strategies usually focus on the control of potential multiple-fire situations in areas and periods with high risk of fire [8]. Under extreme weather conditions, available firefighting resources may be overloaded beyond suppression capacity. In these cases, the ability to Forests 2016, 7, 185; doi:10.3390/f7090185 www.mdpi.com/journal/forests
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