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Isla del Coco is the only oceanic island in the Eastern Pacific with humid tropical climate. Its forests have a particular structure with a unique array of plant species and high endemism. There are few studies on the flora or forest monitoring on the island. The population structure of Sacoglottis holdridgei was analyzed using data from six years with data points taken in 2006 and 2012, including sampling of regeneration in 2012. Sacoglottis holdridgei was the most important tree species, presenting in 2012 the highest Importance Value Index (190.7±21.8), abundance (158.5±40.3 Nha -1 or 39.5 % of the forest) and basal area (15.6 m 2 ha -1 or 72.9 % of the forest). It was present in all three height strata with dominance in the highest. Annual mortality was reported at 3.3 % and recruitment at 1.2 %. The diameter distribution of forest fits the inverted J model, but not for the reported species of which only S. holdridgei tends to adjust for DBH>40 cm. Regeneration fitted the inverted J model with values below those reported for continental forests. Even though it was the dominant species, S. holdridgei showed low regeneration values. This particular condition, give way hypotheses related to the introduction of species, species biology and climate change which could influence the future development of S. holdridgei and forests of Isla del Coco. Rev. Biol. Trop. 64 (Suppl. 1): S263-S275. Epub 2016 Febrary 01.

Modelación de nichos ecológicos basado en tres escenarios de cambio climático para cinco especies de plantas en zonas altas de Costa Rica Climate change generates different responses in the distribution pattern of flora and fauna. According to the predictions of the Intergovernmental Panel on Climate Change (IPCC) through global models, areas that are most affected are the highland areas, due to drastic changes in environmental variables such as temperature and precipitation. That is why ecological niche models with MaxEnt (algorithm based on maximum entropy) were made for the following species: Comarostaphylis

RESUMEN En este documento se describen la estructura y la composición florística de peque-ños árboles y arbustos (1,5 m de altura y hasta 10 cm de DAP), de dos bosques de la llanura aluvial inundable del bajo Ucayali, en la Amazonía Peruana. Estos bosques son del tipo restinga alta y restinga baja, con una inundación anual promedio de alrededor de 1 a 2 meses, respectivamente. Los suelos son entisoles ricos en nutrientes, y la vegetación arbórea forma altas copas cerradas con la presencia de árboles emer-gentes. Se establecieron un total de 25 parcelas permanentes de muestreo cubriendo un área de 0,64 ha. Estas fueron colocadas dentro de seis parcelas permanentes de muestreo de una hectárea cuadrada, en donde se inventariaron individuos (>10 cm DAP). La densidad promedio total y el área basal del sotobosque es de 4 458 plantas/ ha y 5,0 m 2 /ha, respectivamente. Dentro de las familias de árboles más importantes están Moraceae, Leguminosae, Annonaceae, Euphorbiaceae y Lauraceae; mientras que las familias de árboles pequeños y arbustos importantes son Violaceae, Rubiaceae, Melastomataceae y Olacaceae. De un total de 264 especies arbóreas, 208 se registra-ron en la restinga de estrato superior y 204 se registraron en la restinga de sotobosque. El 56% de las especies se encuentran compartiendo los dos estratos de bosque, mien-tras que cerca del 22% están confinados a uno de ellos solamente. Las especies pre-sentes solamente en el sotobosque son predominantemente arbustos o arbolitos, mien-tras que algunas de las especies, presentes solamente en el estrato superior, son probablemente especies de sucesión temprana casi por desaparecer de los bosques. Palabras claves: Zonas húmedas, valor de importancia por familia, valor de impor-tancia por especie, biodiversidad, riqueza de especies, uniformidad de especies.

Introduction: Islands are essential for world biodiversity. Isla del Coco National Park is an oceanic island in which a tropical rain forest grows; however, its ecology and the effect of introduced species are poorly understood. Objective: To evaluate the mortality, recruitment, regeneration, and growth of forest canopy species. Methods: We measured 15 permanent sampling plots (PSP), nine in the Premontane Pluvial Rainforest (PPR), and six in the Cloud Forest (CF); trees with DBH > 5 cm (diameter at breast height) were measured. The sampling regeneration was done within every PSP, along two transects of 1 X 50 m. Data analyses were performed using data obtained in 2006 and 2012 as baseline. Results: In the period 2012-2017, the annual mortality rate in the PPR was 5.75 % and for CF 6.31 %. The yearly recruitment rate in the PPR was 5.38 %, and 5.90 % for CF. For the PPR the total registered regeneration was 5 656 individuals and 8 700 for the CF. Sacoglottis holdridgei reported the highest mortality and the lowest values of recruitment and regeneration. Forest structure fits the inverted J model for most of the tropical forests. Sacoglottis holdridgei define the forest population structure above DBH > 20 cm. But, diameters under 20 cm are strongly influenced by H. succosa, because it reported the highest abundance of regeneration and recruitment. The annual average increase in diameter between forest was statically different (p = 0.0414; N = 15), 0.36 cm/year in the PPR, and 0.33 cm/year the in CF. Conclusions: The PPR and CF differ in the patterns of mortality, recruitment, and regeneration, confirming the uniqueness of these ecosystems. More successful regeneration of H. succosa will lead to changes in structure and composition of forests, mainly PPR. The changes in forest structure will have a strong impact on epiphytic flora, microclimate conditions, and bird nesting such as Gygis alba (White Tern) due to the loss of mature trees of Sacoglottis. The low regeneration of S. holdridgei is associated with the presence of introduced herbivores, their management is needed for restoring the forest.