Secondary forest regeneration on degraded tropical lands

Abstract

Forest plantations established on degraded sites can accelerate natural succession through their effects on vegetation structure, microclimate, and soils. Spatial and temporal patterns of secondary forest species regeneration were studied in permanent quadrats in Albizia lebbek plantation plots and control areas at a degraded coastal pasture in Puerto Rico. Approximately 6.7 years after plantation establishment, a total of 22 tree and shrub species were found in the plantation plots, compared with only one species (Albizia lebbek) found in the control plots. The majority of tree species in the plantation have seeds that are dispersed by either birds or bats, suggesting that the plantation canopy plays a key role in the regeneration process by providing roosting habitat for seed-dispersing animals. Spatial variations in plantation understory seedling populations were found to be associated with both distance from probable parent trees and understory light intensity. These results indicate profound differences between the plantation and adjacent control plots with respect to their provision of regeneration habitat for secondary forest species, and suggest several factors that should be considered in the design of “foster ecosystems” for the rehabilitation of severely degraded tropical forests.