Here we show that wildland fires in an Italian alpine region are ignited mainly by human negligence. 30 % of fires stars in agricultural areas, 24 % in forests. Lightning plays a role in 10 % of the cases, but its importance has been increasing recently. Areas under hot, dry climate are more prone to fire. Cattle grazing reduces the fuel for winter fires, but increases ignition risk in summer. The maps of fire risk that we produce can help to support fire prevention and ecosystem management.