Not only reseeder or resprouter plants: Trait syndromes and post‐fire responses of three iconic Mediterranean woody species

Abstract

Fire can profoundly affect ecosystem dynamics, species distribution and plant traits, especially in open biomes. Post-fire strategies, namely, resprouters and reseeders, offer a useful framework to examine eco-evolutionary relationships between plants and fire. However, whether resprouter and reseeder plants are consistently formed by distinct trait coordination (syndromes) and responses to fire at the intraspecific level and when considering the role of ontogeny, remain underexplored. This is a relevant lack as, within-species, plants can adjust their functioning and trait coordination can vary considerably along ontogeny. To address this gap, we analysed intraspecific trait coordination and post-fire responses, accounting for the effect of ontogeny in three widely distributed and locally abundant Mediterranean woody species: two resprouters (Erica arborea, Quercus ilex) and one reseeder (Cistus salviifolius). We collected 12 plant functional and architectural traits, including intraspecific variability, well related to fire and drought from three sites in Italy. We ran pairwise correlation and multivariate analyses to explore trait syndromes. We conducted linear regressions to examine relationships between fire regime (time since last fire) and trait responses. We then inspected whether fire regime affects key bivariate trait coordination and if ontogeny influences some trait-fire links. Findings are highly species-specific and generally do not align with a priori classification into post-fire strategies. In most instances, we reveal how either one of the resprouter species exhibits trait patterns more similar to those of the reseeder than to the other resprouter species. Fire can strongly affect trait coordination shaping plant functioning, whereas ontogeny influences a few trait-fire links for the reseeder species while it has a weak effect on the two resprouter species. Our study, while limited to three species and three sites, emphasizes the importance of looking at plant life through a continuous and multidimensional lens which contemplates the inclusion of various sources of within-species variability. We acknowledge that a category-based or dichotomous view on plant functional strategies, including post-fire ones, remains valid and justified when working at coarse scales, whereas it can be much less so for trait-based analyses at fine scales.