ABSTRACT
The floristic similarities of 118 permanent plots established in eastern Bolivia were compared using detrended correspondence analysis (DCA) and canonical correspondence analysis (CCA). The Chiquitano dry forest is characterized by a north to south floristic gradient that intergrades with the Amazon flora to the north and with the Gran Chaco flora to the south. However, the forest situated between these two biomes is composed of taxa which are neither Chacoan nor Amazonian, but are a local variant of the seasonal dry tropical forest that is found in other regions of the Neotropics. Species composition varied along both a latitudinal and longitudinal gradient reflecting the floristic differences in the humid forests of southwest Amazon on the Andean piedmont and those of south-central Amazon on the Brazilian shield. The Chiquitano dry forest tree flora, as documented by these plot studies, was not particularly heterogeneous, although forests over calcareous rocks have a different floristic composition when compared with those found on soils derived from granitic rocks. The origin of the floristic gradient is discussed in light of recent discoveries in paleoecology and future climate change.
