The diversity of hemi-epiphytic figs (Ficus; Moraceae) in a Bornean lowland rain forest

The diversity and niche specificity of hemi-epiphytic figs in a lowland dipterocarp forest in Sarawak were investigated in 1998. Twenty-seven fig species (264 individuals, c. 120 ha) colonized a diversity of host taxa (35 families), but densities were very low and only 1.77% of trees >30 cm d.b.h. were occupied. There were no significant associations with host taxa or host-bark roughness but among 11 common species (9 individuals) the distributions of all other parameters (host-d.b.h., height and position of colonization, crown illumination, soil-texture and slope-angle) were significantly different, and we identified five fig guilds. The guilds corresponded to canopy strata, and appeared to reflect the establishment microsite requirements of different species. A fundamental trade-off within the hemi-epiphytic habit was revealed: Species colonizing larger hosts were rarer, because of lower host densities and more specific microsite requirements, but had better light environments and attained a larger maximum size. The single strangler species appeared to escape many of these constraints, and an important source of mortality caused by host-toppling, indicating the advantages of this strategy. Thus, the hemi-epiphytic figs in this community have come to fill a remarkable diversity of niches, despite low levels of competition, through the exigencies of a complex environment.