Influence of fuel conditions on the occurrence, propagation and duration of wildland fires: A regional approach

• Fuel load and status influenced fire occurrence.
• High fuel load was observed in sites affected by fires less than 300 ha.
• Fire spread was not limited by fuel features over 300 ha burned.
• High duration of fires was associated with high fuel load.
• Remote sensing data was useful to understand fire behaviour in our study region.

Wildfires affect Earth's surface every year. Fuels conditions influence fire occurrence and behavior; therefore, their characterization is important for fire risk studies. We analyzed vegetation conditions influencing fires occurrence, spread and duration in semiarid Argentina using satellite and complementary data. MODIS spectral data and GLC2000 map were the main inputs for this study. We analyzed pre-fire vegetation spectral responses of unburned areas and sites affected by fires of different sizes and durations nearby in space and time. Fire occurrence was more influenced by fuel load in shrublands, agriculture and steppes than in forests, where fuel status was most critical. Differences among burned and unburned sites were achieved in less time in shrublands and agriculture than in the steppes and forests due to fuel thickness, type and degradation state. Vegetation conditions also varied between fire sizes. Smaller fires were preceded by high fuel accumulation. From 300 ha burned fuel conditions were not related with fire spread probably due the influence of another variables. Fire duration was clearly influenced by pre-fire fuel quantity. Based on our results, we concluded that satellite data appears as a valuable tool to study fire occurrence and behavior, and to provide useful data for fire prevention.