Metropolitan greenspaces and carbon sequestration potentials in Abeokuta, Ogun State, Nigeria

Abstract

Carbon dioxide (CO2) is the major greenhouse gas and global warming propellant which is released from human activities especially vehicular emission. The study examined carbon sequestration potential of roadsides trees in Abeokuta, Ogun State. The major roads selected were Asero-Obantoko (AO), Brewery-Itaoshin (BI), lyana Mortuary-Idiaba (IMI), Presidential Boulevard Kuto (PBK) and Pansheke-Ojere (PO). After tree identification, concentrations of CO2, CO, NOx, SO2 and H2S along the roadsides were determined using Land-Duo gas analyser. Haga Altimeter, Girth Tape and Range Finder were used to determine diameter at breast height and height of the trees for the estimation of Above-Ground Biomass (AGB). Regression model was used to estimate carbon sequestered by the urban trees. Data obtained were subjected to descriptive and inferential statistics. Mango (Mangifera indica), Gmelina (Gmelina arboreal) and Neem (Azadirachta indica) were identified in all the roads while Cassia (Cassia seamea) were found along BI road, Step tree (Terminalia mentalis) along PBK road, and Masquerade (Polyalthia longifolia) along AO, IMI and PO roads. The non-green spaces zones had (p < 0.05) higher CO2 and other gases compared to the green spaces’ zones. The non-green spaces zones had (p < 0.05) higher CO2 and other gases compared to the green spaces’ zones. Highest AGB 66.82 × 106 kg m-2 was estimated in Neem (Azadirachta indica) along BI roads while highest carbon sequestration of 14273.00 kg m-2 was calculated for Gmelina (Gmelina arboreal) along PO road. Carbon dioxide concentration due to vehicular emission reduced with roadsides trees.