Assessment of land-cover changes and carbon sequestration potentials of tree species in j4 section of Omo Forest Reserve, Ogun State, Nigeria

Abstract

<jats:p>We evaluated carbon stock accumulation on potential of tree species in five forest-types in Omo Forest Reserve of western Nigeria. This included four forest plantations and a natural forest of mixed species. The reserve was stratified into Gmelina arborea, Tectona grandis, Pinus carebeae and Nauclea diderrichii plantations as well as natural forest. Each forest-type was assessed using circular plot method. Plot points were pre-determined using remote sensing. For each point, two circular plots were established, the main plot with a radius of 12.61 m (500 m2 ) and the subplot with a radius of 5.64 m (100 m2 ). In each plot, tree Dbh and height were measured for trees with Dbh ≥10 cm, while only trees with Dbh &lt;10 cm but &gt;2 cm (i.e. 2 cm ≤ Dbh &lt; 10 cm) were considered in the sub-plot. Soil samples were also collected at 10 locations with 2 each in the north, south, east, west and at the plot centre, in each forest-type. The samples were analysed to obtain soil organic carbon. Above- and belowground biomass and carbon stocks were estimated using the appropriate allometries formulated for the tropics. All empirical relationships were included in the existing allometries with Dbh and height as predictors. Landsat images of the reserve in 1991, 2000, 2014 and 2019 were processed and analysed to assess forest degradation. The results revealed that 23-year-old Pinus caribaea plantation sequestered more carbon (35.78±2.73 tons/ha) than 35-year-old Gmelina arborea (18.96±1.82 tons/ha), 43-year-old Tectona grandis (17.75±2.13 tons/ha) and 43-year-old Nauclea diderrichii (17.36±1.87 tons/ha) plantations and natural forest (21.98±2.38 tons/ha). The study showed that stand density influences carbon stock accumulation of forest. It was observed that individual stems of Pinus caribaea were better carbon accumulators than Gmelina arborea, Tectona gransdis and Nauclea diderrichii. The same trend was observed for CO2 captures as Pinus caribaea captured 131.31±10.02 tons/ha with Nauclea diderrichii the least, having a value of 63.71±6.9 tons/ha.&#x0D; Keywords: Biomass, Carbon stock, Degradation, Forest-type, Stand density</jats:p>

Assessment of carbon sequestration of Teak (Tectona grandis Linn. F.) plantation on the campus of University of Ilorin, Nigeria

“…Although, an old forest may not be capturing any new carbon but can continue to hold large volumes of carbon as biomass over long periods (Yusuf et al 2019). This result is contrary to the findings of Adeyemi and Adeleke (2020) who reported a low AGB and BGB for teak in the J4 sector of Omo Forest Reserve, south-west Nigeria. This may be influenced by factors such as tree growth rates, environmental conditions, or management practices.…”

“…Also, the tree biomass may be influenced by the level of some tree growth parameters such as age, height, basal area, stand density, diameters, and volume of trees. Adeyemi and Adeleke (2020) also noted that species differences and stand density significantly influenced the amount of carbon sequestered. Generally, the results also support that teak is one of the most important tree species in carbon sequestration as other studies have revealed.…”

“…(4) Organic Carbon Stock (t/ha) = OC × BD × Soil Depth Where OC = Organic Carbon; BD = Bulk Density Total carbon stock was estimated by summing the carbon contents of all trees per hectare in each age series (which is the combination of the above-ground carbon and the below-ground carbon of trees) and the soil carbon (Adeyemi and Adeleke 2020).…”

“…The SOC increased with depth for the 14 years (2009), 13 years (2010), and 12 years (2011) age series, while it decreased for the 15 years (2008) and 11 years (2012) age series. Meanwhile, Adeyemi and Adeleke (2020) reported that the soil carbon of teak decreased with depths in the J4 sector of Omo forest reserve, while Ashura (2016) submitted that forests have higher SOC compared to other land uses which can be associated with a large annual addition of organic matter in the form of leaf litter, and longer residue time in the soil due to fewer disturbances, which subsequently ends up in higher organic carbon. Generally, the rate of litterfall and dynamics associated with it regulate the litter decomposition in soil and assist in organic carbon storage (Lugo et al 1990).…”

Assessment of Mining-Induced Land Degradation in Ile-Ife, Osun State Nigeria

“…In these studies, the application of GIS and remote sensing as tools for data collection and analysis has a wide area of application in environmental resources management. Remote sensing data, such as Landsat TM, ETM+ and OLI/TIRS were used in change detection analysis (Weng, 2002;Bello et al, 2018;Adeyemi and Adeleke, 2020), to provide information on changing extents and patterns of land degradation caused by mining in the study area.…”