Spatial and temporal variations of overstory and understory fuels in Mediterranean landscapes

•Spatial and temporal variation of fuel characteristics are assessed for vegetation strata.•Overstory and understory fuel characteristics are poorly correlated.•Forest flammability across Mediterranean landscapes relates to climate conditions.•The rate of change of fuel characteristics was weakly affected by climate over the last 25 years.•Fuel management policies should include species-specific information for each stratum.