Assisted recovery of degraded tropical lands: plantation forests and ecosystem stability

Abstract

Plantations of multipurpose tree species can play a critical role in restoring productivity, ecosystem stability, and biological diversity to degraded tropical lands. The present study, conducted at a coastal pasture site in Puerto Rico, compares 4.5-year-old plantation stands of Albizia lebbek (L.) Benth. plantation stands and adjacent control areas. The comparison is concerned with understory species diversity and nutrient storage patterns within vegetation, forest floor organic matter, and mineral soil compartments. Mineral soil (0 to 20 cm depth), organic carbon (OC), and total nitrogen (TN) were both significantly higher in plantation plots (1.70% OC, 0.095% TN) than in control plots (1.44% OC, 0.074% TN). Standing crop mass of herbaceous plants, forest floor organic matter, and fine (<2 mm) roots averaged 160, 349, and 362 g/m² in the plantation plots and 420, 311, and 105 g/m² in the control plots. Nitrogen concentrations within each of these biomass components were, however, consistently higher in the plantation plots. Plantation understory species appear to be efficient “scavengers” of biologically fixed nitrogen and appear to help buffer the system against leaching losses. Species richness was considerably greater in plantation than control plots for grasses, vines, and forbs. Seedlings of several secondary forest species were abundant in the plantation understory, but absent in control plots, suggesting an important role for such plantations in accelerating natural regeneration of native forest species on certain sites.

Citation

Parrotta, John A. 1993. Assisted recovery of degraded tropical lands: plantation forests and ecosystem stability. pp. 169-182 in: Paoletti, Maurizio; Foissner, Wilhelm; Coleman, David. (eds.) Soil Biota, Nutrient Cycling and Farming Systems. Lewis Publishers, Chelsea, MI. 314 p.