Assessing fire propagation empirical models in shrub fuel complexes using wind tunnel data.

Shrubland are one of the main communities affected by wildland fires, both in forested and unforested areas. However, empirical models predicting fire behaviour in these communities are scarce. One reason explaining the lack of knowledge is the difficulty of obtaining data to develop these kinds of models. Wind tunnel experimental fires have been carried out in different shrubland fuel complexes (Ulex europaeus L. and Pterospartum tridentatum (L.) Willk.) collected in Galicia (NW Spain). Rate of spread data recorded in the laboratory tests have been compared with predictions from existing empirical models. The relationship between the rate of spread values observed in the wind tunnel and the values predicted by different empirical equations obtained in field experimental burns is highly significant, although models overestimate the values observed in the wind tunnel. Nevertheless, the high correlation (r between 0.86 and 0.99) allows both values to be considered proportional. Even if the laboratory scale is a limiting factor to study fire behaviour, these experiments are simpler, safer and less expensive than the ones carried out in the field. Therefore, laboratory experiments could be an important complementary source of information to field studies in order to further the understanding of fire behaviour in shrubland fuel complexes.