Composición florÍstica y estructura de un bosque primario del piso premontano pluvial, en San Ramón, Costa Rica

Abstract

A survey of teees (greater than 10 cm in diameter at breast height, DBH), was done in two one-hectare plots of a Tropical Premontane Rainforest in the M. Brenes Biological Preserve, Alajuela, Costa Rica The two plots differed in dominance and number of species (67 and 42), average total density (764 and 486 indlha), percentage of trees within the 10 to 20 cm DBH c1ass (48 and 57%), Holdridge Complexity Index (252 and 142) and Shannon-Weiner Diversity Index (5.45 and 4.18), even though they were less than 1.5 km apart al the same height aboye sea level (900 m). Only 22% of the species coincided giving a Jaccard Similarity Index of 0.1. Differences are tentatively attributed to a steeper topography in tbe less complex plot.