Abstract
The total wet season potential evapotranspiration regime of the lowland savannas is virtually constant, and they can be distinguished from other vegetation classes on this basis alone. It is clear that the savannas occupy a well-defined habitat delimited by the climatic potential for plant growth; this potential is greater than that of deciduous forest regions but less than that of evergreen and semi-evergreen forest regions. The wet season potential evapotranspiration regimes of the natural vegetation have been used to strengthen the basis for defining broad climatic sub-regions for pasture production over tropical South America. This is helping to locate representative sites for testing new grass and legume accessions, and to define ecologically comparable regions for the development and transfer of pasture technology, generally.
