ABSTRACT
In the English language the expression 'in the tropics', for some time, has been used to refer to the area which is, quite literally, in between the Tropics of Cancer and Capricorn. The adjective 'tropical' has been applied to phenomena which are characteristic of the whole or parts of this inter-tropical belt. Botanists and foresters thus refer to 'tropical rain forest' and agriculturalists and pedologists to 'tropical soils'. Confusion about the word 'tropical' has arisen mainly because some systematists, particularly climatologists, have used it to refer to areas in the vicinity of the geographical tropics as distinct from areas around the Equator which they have referred to as 'equatorial'. If this latter usage had achieved any degree of precision, there would be a good reason for retaining it, but since this is not the case, the wider and more general sense will be adhered to here. It must be emphasised, however, that complete avoidance of ambiguity is impossible since biological phenomena do not conform exactly to terrestrial geometry; numerous plant communities and soil types overlap the Tropics of Cancer and Capricorn so that the distributions of so-called 'tropical' phenomena are, to a certain extent, 'sub-tropical'.
