2.3.1.2 Some deciduous tropical trees
Some deciduous tropical tree species behave very counterintuitively in
producing fresh foliage before a dry season ends (e.g. Borchert and
Rivera 2001; Kushwaha et al. 2015). A specific case is Faidherbia
albida A. Chev. (apple-ring acacia), a widely distributed, deep-rooting
tropical tree species of Africa, found with annual rainfall of 200−500
mm. It flushes vegetatively during the dry season, but sheds its leaves
during the rains (Huxley 2001), yet it flowers at the end of the wet
season. Accounting for such counterintuitive behaviour is a challenge,
but it is hard to see a convincing alternative to the postulate of
pathogens driving a shift to deciduousness. Actual support for the
postulate would come if, when such species are grown with no dry season,
the new foliage suffered from pathogens. The success of such a study,
however, would depend on both the presence of the appropriate pathogens
and the nature of the triggers for shedding old leaves and producing new
ones. An alternative driver, namely increased herbivory pressure during
the wet season, seems very unlikely in these cases.