DOI 10.1007/s10531-007-9159-5 ORIGINAL PAPER

Abstract At the edges of tropical rain forest fragments, altered abiotic and biotic conditions inXuence the structure and dynamics of plant communities. In Neotropi-cal rain forests, palms (Arecaceae) are important Xoristic and ecological elements. Palms ’ responses to edge eVects appear to be idiosyncratic and to depend on the level of disturbance at edges. This paper explores how variation in forest structure at the edges of two old-growth forest fragments in a tropical rain forest in western Ecuador aVects palms of diVerent species, life-forms, and size classes. We investigate (1) how edge eVects inXuence the relative proportion of palm adults and juveniles, (2) how distance from the forest edge aVects palm density and species richness, (3) how altered forest structure along edges aVects palm density. We found that at edges (1) palm communities had a lower proportion of adults relative to juvenile individu-als compared to continuous forests, (2) the density of two species of palms and the overall species richness of the palm community tended to decrease toward the edges within forest fragments, and, (3) altered forest structure decreased the density of adult palms. Hence, edge eVects on palms were controlled by the degree of modiWca-tion of the forest structure, and by species responses to edge-related disturbance