2 tab. 10 ref. Sum. (En)

We measured natural regeneration and understory light availability in two plantations in pure and mixed designs in the humid lowlands of Costa Rica. The plantations consisted of 8 native species: Plantations 1: Jacaranda copaia, Vochysia guatemalensis, Calophyllum brasiliense and Stryphnodendron microstachyum; Plantation 2: Terminalia amazonia, Dipteryx panamensis, Virola koschnyi and Albizia guachapele. In Plantation 1, at 3 and 7 years forest tree invasion was higher under V. guatemalensis, while shrubs were more abundant under J. copaia and under mixed-species treatments. In Plantation 2, at 5 years the mixed treatment had the highest number of herbaceous understory species, while D. panamensis had the highest understory biomass. At 7 year, V. koschnyi and T. amazonia had the highest number of woody species. Competition for grasses is a major factor influencing woody invasion under these plantations. High accumulation of litter on the plantation floor may contribute to diminish grass growth and thus encourage woody invasion under the species' canopies.