Phenology of Ficus variegata in a seasonal wet tropical forest at Cape Tribulation, Australia

Abstract

Abstract. We studied the phenology of 198 mature trees of the dioecious fig Ficus variegata Blume (Moraceae) in a seasonally wet tropical rain forest at Cape Tribulation, Australia, from March 1988 to February 1993. Leaf production was highly seasonal and correlated with rainfall. Trees were annually deciduous, with a pronounced leaf drop and a pulse of new growth during the August‐September drought. At the population level, figs were produced continually throughout the study but there were pronounced annual cycles in fig abundance. Figs were least abundant during the early dry period (June‐September) and most abundant from the late dry season (October‐November) through the wet season (December‐April). The annual peak in reproduction actually reflected two staggered peaks arising from gender differences in fig phenology. In this dioecious species, female and male trees initiated their maximal fig crops at different times and flowering was to some extent synchronized within sexes. Fig production in the female (seed‐producing) trees was typically confined to the wet season. Male (wasp‐producing) trees were less synchronized than female trees but reached a peak level of fig production in the months prior to the onset of female fig production. Male trees were also more likely to produce figs continually. Asynchrony among male fig crops during the dry season could maintain the pollinator population under adverse conditions through within‐ and among‐tree wasp transfers.