Carbon Sequestration Of Above Ground Tree Biomass In Tropical High Forests And Monoplantations In Okpon River Forest Reserve, Cross River State, Nigeria

Abstract

This study assessed the above-ground biomass (AGB) of Tropical High Forests (THF) and a 20-35-year-old teak plantation in the Okpon River Forest Reserve, Cross River State, Nigeria. The research used a simple random sampling technique with 26 nested plots in THF and 10 in the teak plantation. A total of 610 trees (435 in THF and 175 in the plantation) were measured for diameter at breast height (dbh ≥5cm). These measurements, along with wood species density, were input into allometric equations to calculate above-ground green biomass, dry biomass, and carbon stock. Results revealed a mean dbh of 42.3 cm in THF and 24.2 cm in the plantation. The THF 
plantation. Average stand volume in the THF was 212.6 m³/ha, higher than the 155.95 m³/ha in the plantation. The tropical high forest had significantly higher biomass and carbon stock, with 423.74 t/ha of green biomass, 307.21 t/ha of dry biomass, and 153.61 t/ha of carbon, compared to the plantation's 164.36 t/ha, 119.16 t/ha, and 59.58 t/ha, respectively. The plantation's high tree density suggests overcrowding, indicating a need for thinning to promote growth. Conversely, the THF's stand density indicates limited anthropogenic disturbance and efficient nutrient uptake. To improve forest productivity, it is recommended to implement better management practices such as boundary cleaning and enrichment planting.