keywords: Carbon sequestration, family value index, sequestered CO2 equivalent, urban parks
Assessment of carbon credit potentials of trees in the Benue State Secretariat Makurdi was done using a non-destructive allometric model, consisting of Above ground Biomass (ABG), Below Ground Biomass (BGB) and Diameter at Breast Height (DBH) using the equation: AGB = Exp [1.627 + 1.393 * Ln(DBH)]. DBH(cm) was measured at approximately 1.3 meter above the ground level on each tree. BGB was determined as 20% of AGB (kg/tree).Furthermore, dry AGB and BGB were determined as 65% of AGB and BGB, respectively, while Total biomass (TB) was determined by the summation of dry AGB and dry BGB (kg/tree). A total of 150 trees (from 15 species and 10 families) were sampled in the study area with Khaya senegalensis (66) being the most abundant. Diversity indices – Importance value index and family value index – were also evaluated to ascertain species and family distribution. Khaya senegalensis (Meliaceae) had the highest IVI (488.9). The DBH class range (cm), 101-150 had the highest frequency followed by 51-100 and 151-200, and the least DBH classes were 0-50 and 201-250, implying trees of moderate height. DBH (cm) and AGB (kg) correlated positively (R2= 0.98, P= 0.000) in all the species sampled, hence AGB increased with increase in DBH. Furthermore, Gmelina aborea had the highest above ground biomass (10935.55), total biomass (8529.73), below ground biomass (2187.11), total sequestered carbon/tree (4264.86), sequestered carbon dioxide equivalent (kg) (15652.05), and sequestered carbon dioxide equivalent (tonnes/tree) (15.65), correspondingly. The study determined the total sequestered carbon (32.7 Tonnes) and sequestered carbon dioxide equivalent (120.23 tonnes/tree); thus, elucidating the potentials of these species and the urban park in carbon sequestration and climate change mitigation.