White-sand vegetation of Brazilian Amazonia ( caatinga).

Abstract

The described vegetation type, 'Amazon caatinga', is distinguished by its white-sand soil, scleromorphic physiognomy, and unusual floristic composition. The scleromorphic physiognomy of the caatinga indicates a lack of nutrients and/or periodic water deficiencies in the soil. Extreme edaphic conditions and the insularity of these sites have probably acted as powerful selective forces, generating a biota characteristically low in diversity and high in endemism. Numerous endemics may currently face extinction due to widespread burning. Repeated fires on white-sand sites result in the effective arrest of succession.-from Author