Early indications of success rehabilitating an underperforming teak (Tectona grandis) plantation in Panama through enrichment planting

Enrichment planting can be an effective strategy for increasing the ecological and economic value of timber plantations, but success depends on appropriate matching of under- and overstory species and site conditions. This case study in the Panama Canal Watershed explores the viability of enrichment planting for rehabilitating underperforming teak ( Tectonia grandis) plantations, which are common in the area. Two high-value timber species native to the neotropics, Dalbergia retusa and Terminalia amazonia, were underplanted in an established teak plantation at the Agua Salud research site in the province of Colon, Panama. Seedling survival, basal diameter, height, total biomass and relative growth rate were assessed for the two years following planting. In contrast with the widespread belief that teak is a poor nurse tree, both species achieved promising early growth with low mortality in plantation understory conditions. Neither understory light availability nor combined above- and below-ground effects of crowding pressure from teak strongly predicted growth of either species. D. retusa, thought to be more shade-tolerant, performed equally across a range of intermediate light levels whereas T. amazonia, thought to be more heliotropic, performed best at the highest light levels, though light relationships explained little variation in seedling growth. These early findings support the suitability of either species for use in enrichment plantings in established, underperforming teak plantations in the Panama Canal Watershed. Longer-term research is needed to evaluate the potential of enrichment planting to increase profitability and ecosystem services such as carbon sequestration and water resource management in these plantations.