Okoh Thomas, Okekporo Efe Stephen and Iorja Fatilen Solomon
ATrees and herbs are important components of forests and urban parks have been reported as vital carbon sequesters in terrestrial ecosystems. However, there is limited data on carbon credit of herbaceous plants within the study area. Carbon credit potentials of 1532 herbs belonging to 68 species and 20 plant families were evaluated in ten parks in Joseph Sarwuan Tarka University Makurdi, Benue State, Nigeria. Samples were collected using 1 m 2 quadrats; herbaceous and litter biomass [dry biomass] were determined as 50% of oven dry weight. Total sequestrated carbon [TSC] of herbs was estimated as 50% of dry biomass. Sequestered carbon dioxide equivalent SCO2 E (kg) was assessed using the equation: TSC x 3.67. Soil organic carbon [SOC] was determined by Walkley–black method and subjected to One-way Analysis of Variance [ANOVA]; Tukey-HSD [post-hoc] was done for means separation. The relative richness/diversity of species was estimated using Shannon-Weiner Diversity Index. Synedrella nodiflora was represented in all 10 parks while Sporobolus pyramidalis recorded the highest species frequency (137). Forestry Park gave the highest species frequency (251). Also, family Poaceae gave the highest family frequency (561), followed by family Asteraceae (295). Veterinary Park gave the highest species diversity index (2.96). Furthermore, NUBESS Park gave the highest herbaceous biomass (0.111 kg), TSC (0.056 kg) and SCO 2 E (0.204 kg); while Student Union Park gave the highest herbaceous litter biomass (0.115 kg), TSC (0.057 kg) and SCO 2E (0.21 kg) respectively. The total herbaceous biomass, TSC, and SCO2E of all parks (kg/m 2) were 0.74 kg, 0.37 kg and of 1.37 kg respectively; while the total herbaceous litter biomass, TSC and SCO 2E were 0.46 kg, 0.23 kg and 0.85 kg respectively. Soil organic carbon was significantly different (P < 0.05) between NUBESS and Forestry parks. The average SOC of JOSTUM parks was 0.85 g kg -1. JOSTUM parks are a good repository of SCO 2 E and SOC, which is indicative of their carbon credit potentials, and should be properly utilized for biodiversity conservation and climate change mitigation.