Functional responses of Mediterranean flora to fire: a community-scale perspective

Fire regime is predicted to change, particularly in Mediterranean climate regions, towards more severe and frequent fire events. From a predictive perspective, trait-based ecology offers a comprehensive framework to characterize vegetation responses to fire. Since fires induce erosion and decrease soil nutrients, species’ functional traits and their distribution at community level should reflect these changes. Despite a vast literature focused on plant traits involved in resistance to fire, quantification of community trait responses to fire is lacking, particularly for traits that are linked to resource strategies. Here, we emphasis on plant traits related to morphology (height, specific leaf area, stem and wood density) and resource acquisition strategies (leaf nitrogen, leaf dry mass, seed dry mass). We compiled three different databases compiling vegetation, fire and functional traits for the flora of Southern France. We analyzed the relationships between these three components at both species and community levels. Fire numbers and area burnt did not impact species trait distributions. At community level, a clear pattern emerged between the number of fires and the distribution of different traits considered, with two main axes: on the positive PC2 axis vegetative height and seed mass; and on negative PC1 axis leaf carbon and positive PC1 axis nitrogen content and leaf area. We also showed that vegetative height is positively correlated to the aridity index distribution in the region studied.