Demography, Dispersal and Production of Pandanus tectorius (Pandanaceae) in Fiji

Abstract

Populations of Pandanus tectorius (Pandanaceae) were examined at coastal and peat swamp sites in Viti Levu, Fiji. Rates of leaf production (10-90 year^-1), stem and branch growth (2-80 cm year^-1)) were determined and used in conjunction with observations of the number and spacing of leaf scars and peduncle scars to estimate plant age. A semiprostrate juvenile phase of 4.5-9 years is followed by erect trunk growth for c. 5-12 years followed by a flowering phase lasting 40 years or more. Male plants form about 30 branches and flower annually, while female plants form about 16 branches and flower biennially. Each fruit forms about 76 phalanges (drupes) and each phalange contains up to eight embryos, although many were parasitised by insect larvae. Dispersal of phalanges by Pteropus tonganus (Chiroptera), water, man and crabs or rats was recorded. In swamp sites occasional fires kill many of the small-medium-sized plants, while cyclones damage and kill large plants at all sites. Because infrequent but severe destructive events limit survivorship, it is difficult to define characteristic natalities or mortalities. The sex ratio of the population indicates a slight preponderance of females. The allocation of biomass to reproduction is estimated to be c. 34% in females and 15% in males, at 60 years.