Photo above from Takhtajan (1969) Flowering Plants Origin and Dispersal
The forest on Pulau Peucang, an island included in the Udjung Kulon National Park in East Java is dominated by tall Ficus nervosa forest. One can speculate that eruptions of the numerous volcanoes in the area have frequently destroyed and sterilized the vegetation on the surrounding islands which are then recolonized firstly by wind borne seeds followed by fruit bat defecated seeds- particularly figs. The plants that establish first have first mover advantage and dominate the vegetation until next volcanic eruption when the whole cycle of colonization and renewal starts again.
Thornton et al. (1969) The role of animals in the colonization of the Krakatau islands
Note that Ficus pubinervis is a synonym for Ficus nervosa. See also Ficus nervosa: Peucang Island Resort.