Island effect on the taxonomic, functional and phylogenetic biodiversity in Bahía Málaga, Colombia

Abstract

Tropical rainforests harbour at least 50% of the world’s biodiversity, and such richness can be measured in the number of species per area unit. The present study sought to assess the effect of geographic isolation on the vegetation structure and taxonomic, functional and phylogenetic diversity of the woody vegetation in the National Natural Park Uramba, in Bahía Málaga, Colombia. For this purpose, a 1 ha plot (100x100 m) was established in Isla Palma, within which individuals with DBH>10 cm were recorded. The following functional traits were evaluated: leaf area (mm²), specific leaf area (mm²/mg), leaf dry-matter content (mg), leaf type (simple or compound), basal area (m²), wood density (g/cm³), fruit length (cm), seed length (cm) and type of dispersal (biotic or abiotic). The structural and functional aspects were compared with data from the permanent plot in La Plata, which is in the continental area of the PNN Uramba. The diversity, richness and taxonomic composition was lower in Isla Palma. The species composition suggests a good degree of conservation in the forest since no other families typical of disturbed zones were found amongst those with higher abundance. In Isla Palma, higher specific leaf area and lower wood density values were observed. Differences in the functional and phylogenetic biodiversity were not observed between the insular and continental areas, which suggests that an ecological filter prevents the colonization of some species in Isla Palma. Rather, an exchange of species occurs, and they cover the different functional niches with a similar phylogenetic representation.