THE EFFECT OF HUMAN ACTIVITY ON THE STRUCTURE AND COMPOSITION OF A TROPICAL FOREST IN PUERTO-RICO

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