ABSTRACT
The cerrado vegetation of São Paulo and neighbouring states occurs under more extreme environmental conditions, especially lower temperatures (occasionally with severe frosts), and a shorter dry season than the core area of the biome. As a consequence, these southern cerrados form a distinct phytogeographical region, which can be locally divided into two separate floristic (and physiognomic) groups: (1) areas covered by cerradão (associated with more fertile soils) and (2) areas covered by sparser vegetation, e.g. cerrado sensu stricto (associated with very poor and sandy soils). The southern cerrado areas are bordered by the Atlantic forest, which exerts a strong influence on their flora. In recent years, a rapid physiognomic and floristic change has taken place at the southern limits of the Cerrado Biome, especially in São Paulo state: strong protection against fire has caused open forms of cerrado vegetation to change into closed cerradão. The southern cerrados contain some of the floristically richest sites in the cerrado domain and require special protection by conservation strategies.
