The phytogeography of the seasonally dry tropical forests in Equatorial Pacific South America

The origin, current distribution and floristic links of the seasonally dry tropical forest formations in Equatorial Pacific South America (Ecuador, Peru) are assessed by means of multivariate analyses using information from 62 floristic checklists from Neotropical dry forests. Three geographical forest groups are found: (1) coastal Ecuador and Peru plus the Peruvian dry Inter Andean valleys; (2) Central America-Caribbean (including northern South America); and (3) a Bolivian-Argentinean dry forest province. Plate tectonic events, especially the long isolation of South America until the closure of the Isthmus of Panama, the uplift of the Andes and climatic events during the Quaternary are suggested as the causes for these divisions.