The effect of human activity on the structure and composition of a tropical forest in Puerto Rico

Abstract

From European settlement to the 1940s, the Bisley watersheds of the Luquillo Experimental Forest, Puerto Rico, were used for agroforestry, selective logging, charcoal production, and timber management. Each of these activities affected different parts of the landscape in different ways and at different times. After nearly 50 years of unhindered regeneration, six impacts remain apparent: (1) shifts in the dominance and age structure of canopy species; (2) immigration of subcanopy crop species and the establishment of banana as a riparian dominant; (3) increases in the importance of canopy species used for coffee shade; (4) the impoverishment of certain commercial timber species; (5) an increase in the density of palms around abandoned charcoal kilns; (6) a reduction in the regeneration of canopy species around abandoned charcoal kilns. Changes in the above-ground nutrient pool may also have occurred. Human disturbances in the study site were progressive rather than discrete events, had adverse impacts on forest regeneration, and increased the spatial heterogeneity of the forest.