Studies in Urban Ecology: Strangler Figs in the Urban Parklands of Brisbane,Queensland, Australia

This study investigated the establishment dynamics of strangler figs and the constraints on their development in the urban parklands of Brisbane, Queensland, Australia. Of 3580 trees and palms in the study parks, approximately 5% support at least one Ficus species. Six Ficus species occur epiphytically in older parkland. Four are Brisbane natives: F. macrophylla, F. obliqua, F. platypoda and F. virens; and two are from elsewhere in Australia: F. benjamina and F. rubiginosa. A lack of pollinator wasps in the Brisbane area prevents exotic and other native Ficus spp. from reproducing. Though they form predominantly open communities, the percentage of phorophytes (support trees) in the study parks is similar to that associated with natural, closed communities. Ficus spp. become established in structural features that accumulate humic soil, such as the forks of trunks and branches on trees, and behind marcescent leaf bases on palms. Plants with few humus pockets support few Ficus species. Environmental factors such as atmospheric quality, canopy shade, bark texture and whether or not a park is irrigated, seem not to be consequential to Ficus establishment. Significantly greater numbers of Ficus occur on deciduous trees, perhaps because avian seed dispersers favour them as perches over evergreen trees. Ficus also occur significantly more frequently on the western sides of palms with marcescent leaf bases. These western flanks offer shelter from the prevailing sea breezes: fewer Ficus are therefore likely to be torn from these sides in strong winds.