Assessment of Tree Stand Growth Characteristics and Quantitative Status of Selected Forest Plantations in Rivers and Bayelsa States, Nigeria

Abstract

Tree species provide essential ecological, economic, and livelihood benefits, yet plantation forest resources in the Niger Delta remain insufficiently documented for evidence-based management. This study assessed tree stand growth characteristics and the quantitative status of selected forest plantation sites in Rivers and Bayelsa States, Nigeria. A complete enumeration approach was used to measure all trees encountered within the defined plantation boundaries. Diameter at breast height (DBH), total tree height, crown size, basal area, and stem volume were assessed using standard forest mensuration procedures. Species identification was undertaken with support from qualified taxonomists and plantation owners. The results showed marked interspecific and inter-site variation in stand growth characteristics. At IITA, Onne, Lophira lanceolata recorded the highest basal area per hectare, while Pinus caribaea showed the highest stem volume. At FRIN, Onne, Treculia africana had the highest basal area, whereas Lovoa trichilioides recorded the highest stem volume. Irvingia gabonensis was the only domesticated tree species recorded at both Okilogua–Akinima and the Bayelsa State smallholder plantation, but its growth performance differed considerably between the two sites. These findings indicate that plantation productivity in the study area is influenced by species characteristics, site conditions, and management history. The study provides baseline data to support sustainable plantation management and species prioritisation in the Niger Delta.