La Regeneration Naturelle D'une Espece Autochore de La Foret Guyanaise: Eperua falcata Aublet (Caesalpiniaceae)

Abstract

The natural regeneration of Eperua falcata Aublet (Caesalpiniaceae) a common autochorus species, was studied an a 2500 m2 plot in Guiana. Flowering occurs during the dry season and fruits mature during the humid season. Seeds are dispersed when humidity decreases enough to promote bursting of the pod. Nearly 60 percent of the seeds fall less than 10 m from the parent tree, and the maximum dispersal distance is 30 m. Seeds are slowly eaten, and predation by rodents (the principal predators in the studied area) is not distance-dependent. Desynchronisation of flowering and consequent production of fruits during the dry season is followed by high rates of abortion and seed predation. Seedling mortality is low and their distribution under and around the parent tree is nearly the same as that of the seeds. The incomplete destruction of seeds and seedlings in the vicinity of the parent tree conflicts with the Janzen-Connell model. Seedlings maintain themselves during a long time under closed canopy and a small increase of light intensity permits growth in height of several cm a year. Annual mortality of small seedlings is higher and the growth rate is slower than those of large seedlings. Saplings (> 100 cm in height) are principally located between 10 and 15 m from the nearest parent tree, but outside the limit of the crown. This distance corresponds to half the distance between two adjacent trees, on average. This, in turn, corresponds with the major population recruitment zone of Eperua falcata, maintaining this species at a high density.