Abstract

The Dominican Republic has an important area of mountain forests, whose communities are highlythreatened, and are also among the least studied tropical ecosystems with respect to the factors thatdetermine their structure and composition of species. For this reason, the objective of this work was toevaluate the effect of the altitudinal gradient on the diversity and tree structure of the broadleaf forestof the Upper Yaque del Norte Basin. Sample units in three altitudinal ranges (RA) were analyzed, com-paring their diversity and structure indices. 2800 individuals belonging to 34 families, 53 genera and59 species were recorded. The diameter distribution of the individuals presented an arrangement of“inverted J” for the three altitudinal ranges. Differences in diversity were obtained for the altitudinalranges, with RA1 presenting the lowest value in dominance and higher values in equity, richness anddiversity, followed by RA3 and RA2 respectively, although these differences did not show statisticalsignificance. The Upper Yaque del Norte Basin presented lower richness values than other tropicalforests, mainly explained by anthropic actions. The forest structure variables did not show a relation-ship with the altitudinal gradient, obtaining a distribution whose trend would reflect the successionalcharacteristic of the forest. Diversity indices were not related to altitude, which would be explained bythe environmental heterogeneity of the study area.