Floristic diversity of patches generated by protected Ficus ‘trees outside forests’ in agricultural landscapes in Madagascar

Abstract

Ficus trees play an important role as key species in both ecological and sociocultural networks in Madagascar. This study focused on species of isolated Ficus growing in agricultural areas adjoining a forest corridor linking the Ranomafana and Andringitra National Parks in east-central Madagascar, with the aim of understanding the structural and floristic characteristics of the vegetation regenerating under these Ficus ‘trees outside forests’. Two main aspects were studied: (1) the characteristics of the habitats under the crown of isolated Ficus species (Ficus tiliifolia, Ficus reflexa and Ficus lutea), and (2) the specific structure and composition of the vegetation under these Ficus trees: minimum area, species richness, floristic regularity, diversity and similarity, biological type, vegetation type, proportion of annual and herbaceous species, and seed dispersal methods. The results indicate that each of these three Ficus species has its own community composition. The vegetation under F. reflexa is a shrubby formation dominated by autochorous and zoochorous species located on high slopes with a minimum area of 6–12 m². The vegetation under F. lutea is a highly anthropized herbaceous formation dominated by autochorous species located on high slopes at an altitude of 1150–1200 m, with a southwest exposure and a minimum area that ranges from 6 to 9 m². Under F. tiliifolia, different types of plant formations are found in different topographic positions: herbaceous, shrubby or tree-like, with different modes of seed dispersal.