Forest regeneration under Tectona grandis and Terminalia amazonia plantation stands managed for biodiversity conservation in western Panama

Plantations of Tectona grandis in Central America are widely perceived to suppress forest regeneration in their understories, yet few studies have tested this assumption. We surveyed the understory woody vegetation growing in 7-year-old stands of T. grandis and the native tree species Terminalia amazonia in a plantation in western Panama that was managed with both commercial timber and biodiversity conservation objectives. We predicted that if T. grandis suppressed forest regeneration then the understories of T. grandis stands would have a lower density of woody stems, smaller stems, and fewer species than stands of T. amazonia. None of our predictions were supported. Densities of woody stems were 0.56 ± 0.21 m−2 (mean ± SE) and 0.64 ± 0.10 m−2 in T. grandis and T. amazonia understories, respectively. Stem height structure was similar under both species, where stems