Widespread deforestation has led to an increase in secondary forest in the tropics. During the late 1940s in Puerto Rico, forest covered only 6% of the island, but a shift from agriculture to industry has led to the increase of secondary forest. This study focuses on the regeneration of forest following the abandonment of pastures and coffee plantations located in the karst region of Puerto Rico. Alluvial terraces and sinkholes were the principal features used for pastures, shifting agriculture, and coffee plantations, whereas mogotes (limestone hills of conical shape) were burned periodically or cut for charcoal or wood production. Abandoned pasture sites had a greater woody species diversity in comparison with coffee sites. The density of woody stems was greater in the abandoned pasture sites and Spathodea campanulata was the dominant species. In coffee sites Guarea guidonia was the most abundant species. There was no difference in basal area between the two land uses. Canonical Correspondence Analysis applied separately to adults and seedlings clearly separated each community according to land use. Seedling composition in coffee sites indicates a resistance to change in terms of the dominant species while in the pasture sites the composition will change as the dominant species S. campanulata is replaced with more shade tolerant species. Patches of forest that remained on the steep sides of mogotes and the presence of bats appears to have enhanced forest recovery, but the land use history of these sites has affected the pattern of regeneration and will continue to affect forest dynamics for many years. The karst area is a critical environment for water resources and biodiversity and its conservation and restoration is essential. (C) 1998 Elsevier Science B.V. All rights reserved.
