Flammability assessment of Mediterranean forest fuels

The time-to-ignition of various dominant Mediterranean forest fuels was measured during laboratory tests, in order to develop a relative flammability classification and determine the moisture of extinction of these fuels. The tests were performed with an ignition apparatus manufactured according to the ISO standards (ISO 5657-1986E) and under a wide gradient of fuel moisture contents, ranging from air-dry to fresh foliage. Moisture content was the single most significant factor that affected fuel flammability. Regression models were developed between the time-to-ignition and the moisture content values of all the fuels tested, and subsequently, were used for the relative flammability ranking of these fuels. Fuel moisture of extinction was assessed to have a threshold value ranging from 40% to more than 140% o.d.w. for the species tested. The flammability ranking of natural fuels can be useful in fuel hazard assessment and fire danger rating, thus facilitating the judicial fire management planning in wildlands and at the rural-urban interface.