Abstract. Modeling and assessing the factors that drive forest fire ignitions
is critical for fire prevention and sustainable
ecosystem management. In southern Europe, the anthropogenic component of wildland fire ignitions is especially
relevant. In the Alps, however, the role of fire as a component of disturbance regimes in forest and grassland ecosystems
is poorly known. The aim of this work is to model the probability of fire ignition for an Alpine region in Italy using
a regional wildfire archive (1995–2009) and MaxEnt modeling. We analyzed separately (i) winter forest fires, (ii) winter
fires on grasslands and fallow land, and (iii) summer fires. Predictors were related to morphology, climate, and land use;
distance from infrastructures, number of farms, and number of grazing animals were used as proxies for the anthropogenic
component. Collinearity among predictors was reduced by a principal component analysis. Regarding ignitions, 30 % occurred in
agricultural areas and 24 % in forests. Ignitions peaked in the late winter–early spring. Negligence from
agrosilvicultural activities was the main cause of ignition (64 %); lightning accounted for 9 % of causes across the
study time frame, but increased from 6 to 10 % between the first and second period of analysis. Models for all groups of
fire had a high goodness of fit (AUC 0.90–0.95). Temperature was proportional to the probability of ignition, and
precipitation was inversely proportional. Proximity from infrastructures had an effect only on winter fires, while the density
of grazing animals had a remarkably different effect on summer (positive correlation) and winter (negative)
fires. Implications are discussed regarding climate change, fire regime changes, and silvicultural prevention. Such
a spatially explicit approach allows us to carry out spatially targeted fire management strategies and may assist in
developing better fire management plans.
Modeling anthropogenic and natural fire ignitions in an inner-alpine valley
