Growth and effects of thinning of mixed and pure plantations with native trees in humid tropical Costa Rica

Background

As reforestation with native tree species gains in popularity, more information about proper management is needed. This study examines the growth and responses to thinning of ten native species in mixed and pure-species plantations in the Caribbean Lowlands of Costa Rica.

Research goals & methods

Trees were planted at a 2x2m spacing in 32x32m plots and either left unthinned or thinned at 3 and 6 years to 4x4m spacing. While thinning resulted in net positive diameter increases for all trees, basal area and volume remained the same or decreased with thinning. At 9-10 years of age, the species with best growth in diameter and volume were Vochysia guatemalensis, Terminalia amazonia, Jacaranda copaia, Virola koschnyi and Vochysia ferruginea. Most species had better growth in mixed than in pure-species plantations, resulting in higher overall volume; however, the slower growing species Calophyllum brasiliense and Genipa americana grew better in pure than in mixed stands.

Conclusions & takeaways

Trees responded to thinning with increased diameter growth, while height was not generally influenced by thinning. The authors suggest that tight initial spacing and early thinning with high extraction of stems can improve growth and timber quality of stands.