Modelling functional response of reptiles to fire in two Mediterranean forest types

Abstract

Fire is one of the main disturbances to terrestrial environments, transforming habitat structure and affecting community composition. Coupled with fire, forest type and vegetation structure modulate the taxonomic response to fire by ectotherm organisms such as reptiles. The response of each reptile species to fire is based on their functional attributes, which make some species resilient to fire and others vulnerable to that disturbance and only adapted to long-unburnt landscapes. We studied the functional response of a reptile community at 13 burnt sites within the African rim of the Western Mediterranean, and in two contrasting forest types, i.e. native cork oak forests (five sites) and pine plantations (eight sites). We compiled seven functional traits for the reptile species in the study areas, and quantified reptile functional diversity at each sampled plot. Variation in this index was examined from burnt to nearby unburnt plots, both in cork oak and pine forests, with generalized linear mixed models. Redundancy analysis was used to identify which functional traits were associated with particular plot types. We found 2149 individual reptiles from 15 species. The functional response of reptiles to fire was forest-type dependent: functional richness did not change with fire in cork oak forest plots, but increased with fire in the pine plantation ones. High reptile functional richness in cork oak plots was due to high species richness in this forest type. The functional-redundancy analysis showed that cork oak forest hosts a reptile community functionally composed of small Mediterranean ground- and rock-dwelling lizards. In pine plantation plots, however, saxicolous geckos and phytophagous tortoises indicate the availability of other microhabitat and food resources to be exploited by reptile species with different functional traits.