Search

Trees species-based carbon-stock estimates are rare in Nigeria. Therefore, we investigated individual trees’ abilities using non-destructive approach with systematic sampling technique. One hundred circular plots were laid, using pre-classified Landsat-OLI/TC image of Borgu Sector. Plot centres were located and marked with global positioning system receiver. The main plots with 12.61 m radius (500 m²) were subdivided into subplots of 5.64 m radius (100 m²). Trees with diameter at breast height (Dbh) ≥10 cm were measured in the main plots, while trees with ≥5 but <10 cm Dbh were considered in the subplots. Species identification and measurements were executed. Core samples were collected at breast height using 5 mm increment borer. Core samples were oven-dried at 70°C to constant weights. Wood densities were then calculated as oven-dried weights/fresh volumes. Above-ground carbon were determined as 50%-biomass. Soil samples were diagonally collected at three points within sample plots at two depths, using core sampler and soil auger for 600 samples. Samples were air-dried, ground and sieved through a 2 mm sieve. Core sampler and rings were used for measuring bulk density. Samples were oven-dried for 24 hours at 105°C. Soil organic matter was determined by Fe2SO4 titration of an acid-dichromate digestion, and organic carbon concentration was calculated. Tree carbon data were analyzed using allometric equations involving wood density, Dbh and tree-height and ANOVA. Thirty-five tree species in 16 families were encountered. Detarium microcarpum was the most frequently occurring (18.8%). Tree species richness, diversity and importance value indices were 2.852, 4.779, and 41.76 ± 35.41, respectively. Vitellaria paradoxa and Afzelia africana were the only vulnerable species identified. Trees with larger-Dbh sequestered more carbon. Consequently, Adansonia digitata with a mean Dbh of 111.4 ± 0.00 cm sequestered the highest amount (2.8 tons/ha), which were significantly different from others (p < .05). Securidaca longipendiculata had the least carbon stock (0.001 ton/ha). Meanwhile, soil carbon were higher in plots dominated by Acacia kosiensis, V. paradoxa, and Grewia mollis at 0.006758 ton/ha, averagely 0.073 ± 0.0021 ton/ha of carbon-stock and CO2 of 0.271 ± 0.010 ton/ha sequestered, respectively. [ABSTRACT FROM AUTHOR]

The study involved assessment of changes in Oba Hills Forest Reserve between 1984 and 2020 and simulated future scenario in the wake of rising impactful land uses in the protected forest land. Landsat TM, ETM+, and OLI/TC of 1984, 1990, 2000, 2010, and 2020 were acquired from the United States Geological Survey. Ground-truth data were collected to enhance imagery re-classifications. The acquired images were pre-processed and processed using ArcGIS 10.5 to characterize land-use and land-cover changes in the area. Past changes between 1984 and 2020 were evaluated, and a possible future outlook was determined. Image classification accuracy was assessed using Kappa's and other accuracy statistics and confusion matrix. Five land-cover classes were distinguished. The result revealed consistent losses of forest covers over 36-year period. There was a gross loss of 42.7% (1519 ha) in total forest covers within the period at 1.2% yr-1. Specifically, primary and secondary forests shrank by 12.3 and 66.8% between 1984 and 2020, respectively, whereas agriculture and grassland rose by 145.2 and 258.8% at 4 and 7.2% yr-1, respectively. Prime drivers of forest losses were subsistence agriculture and cocoa farming cum illegal timber extractions through flitching. These may have had severe negative impacts on faunal population while subjecting forest-dependent rural populace to livelihood challenges. On the other hand, critical components of the ecosystem may also be in jeopardy due to forest degradation, fragmentation, and eventual loss of high conservation values. Therefore, effective forest protection and conservation means, like providing alternative livelihood means, afforestation programs, and multi-stakeholder fore st management strategies, are advised. [ABSTRACT FROM AUTHOR]

Copyright of African Journal of Ecology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)