GAP-PHASE REGENERATION IN SELECTIVELY LOGGED LOWLAND SWAMP FOREST, NORTHEASTERN COSTA-RICA

For sustainable logging to be achieved in tropical forests, there must be successful gap-phase regeneration to restock: the logged-over area . This study examined three aspects of gap-phase regeneration in selec tively logged lowland swamp forest of northeast Costa Rica. First, log ging gaps were censused immediately after extraction to determine the density of advanced regeneration. Stem density and basal area of resid ual trees greater than or equal to 10 cm dbh in logging gaps was >85% lower than undisturbed forest, and all trees in gaps had sustained str uctural damage. The common canopy species Pentaclethra macroloba (Faba ceae) was the most abundant species in gaps whereas the timber tree Ca rapa nicaraguensis (Meliaceae) was absent from all censused gaps. This suggests that canopy replacement, particularly by Carapa, will depend on trees <10 cm dbh or by seed input into logging gaps. Second, the d iversity of the understorey was compared with. 6-y old single-tree and multiple-tree logging gaps. Multiple-tree logging gaps were the most diverse, but dominated by two ruderal species; however many shade-tole rant species were present in those gaps. This indicates that controlle d selective logging can result in a localized shift in species composi tion, but that logging gaps should return to pre-logging composition w ith time under a carefully implemented, controlled harvesting regime. Finally, this study found a significant effect of a fringing Carapa tr ee on logging gap seedling density. Thus, seed arrival into gaps is a barrier to logging gap regeneration, particularly for a large-seeded t ree species. Gap-phase regeneration by a large-seeded tree species in managed forest would benefit from seed broadcasting into gaps.