Tree community patterns in seasonally dry tropical forests in the Cerros de Amotape Cordillera, Tumbes, Peru

A phytosociological study was conducted in six 1-ha seasonally dry forest samples in selected locations on the Cerros de Amotape Cordillera in north-western Peru. This is the first quantitative study of this vegetation formation in the region, and the findings indicate higher density and richness values than previously thought for the country. The plots varied markedly in species richness from 6 to 25 species, with densities per hectare between 55 and 524 individuals. The most important families were the Bombacaceae, Fabaceae, Bignoniaceae, Combretaceae, Burseraceae and Capparidaceae. At the species level, Caesalpinea glabrata, Tabebuia spp., Terminaliavalverdeae, Burseragraveolens, Eriothecaruizii and Ceibatrichistandra are the most widespread and abundant species. Sorensen similarity indices consistently grouped drier, species poor west facing plots together, while the plots located in more mesic areas either east facing or on the ridges of the Amotape Cordillera were more species rich and similar between them.