Characterizing potential wildland fire fuel in live vegetation in the Mediterranean region

Key message: Fuel moisture and chemical content affecting live plant flammability can be measured through laboratory and field techniques, or remotely assessed. Standardization of methodologies and a better understanding of plant attributes and phenological status can improve models for fire management. Context: Wildland fire management is subject to manifold sources of uncertainty. Beyond the difficulties of predicting accurately the fire behavior, uncertainty stems from incomplete understanding of ecological susceptibility to fire. Aims: We aimed at reviewing current knowledge of (i) plant attributes and flammability: fuel moisture and chemical content in leaves; (ii) experimental evaluation of flammability in the laboratory and in the field; and (iii) proxy evaluation of flammability: vegetation cover assessment at large scale, fuel seasonality, and biomass distribution using remote sensing and Light Detection and Ranging (LiDAR) techniques. Methods: We conducted a review of scientific literature from the last two decades on the three selected issues, with a specific focus on the Mediterranean region. Results: We have evidenced important knowledge gaps: (i) developing standardized methodologies for laboratory- and field-scale assessment of vegetation flammability; (ii) introducing reliable approaches to test the impact of biogenic volatile organic compounds on fire spread; (iii) improving the analysis of spatiotemporal changes in vegetation dynamics, acknowledging distinctive vegetation phenological status as a relevant driver affecting leaf biomass and moisture contents; and (iv) further exploring the processes that shape fuel dynamics to understand how fuel characteristics change over time and space. Conclusion: We propose some improvements in the current knowledge of vegetation science and wildland fire ecology, aiming to generate more realistic models and effective planning in support of fire management in the Mediterranean basin.