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Carbon-dioxide sequestration potential of tree species in Nigerian Tertiary Institutions: A case study of Ondo State, Nigeria

100%
Lawal A., Ayeni O., Ayanniyi O.
World News of Natural Sciences
|
2023
|
vol. 50
247-257
EN
Carbon dioxide (CO2) is one of the most abundant greenhouse gases and a primary agent of global warming. It constitutes 72% of the total anthropogenic greenhouse gases, causing between 9-26% of the greenhouse effect. This study focused on carbon-dioxide sequestration potential of trees in four tertiary institutions (Federal University of Technology Akure, Adekunle Ajasin University Akungba Akoko, Rufus Giwa Polytechnic, Owo, and Federal College of Agriculture Akure) in Ondo State, Nigeria. Identification of trees located in built up areas, car parks and walk ways of each institution was done with an experienced taxonomists. Tree variables such as diameter at breast height (dbh), diameter at the base (Db), diameter at the middle (Dm), diameter at the top (Dt) and total height (Ht).) were measured using Spiegel relaskop and girth diameter tape. Carbon storage estimation was estimated using non-destructive method. Of the 100% CO2 in the institutions under this study, AAUA had 92.22%, FUTA had 3.40%, RUGIPO had 4.99% and FECA had 0.59% respectively. The amount of carbon-dioxide estimated for each institution in this study were comparably higher than what was obtained for Strict Nature Reserve (593.68 tons/ha) and Enrichment Planting Forest (326.14tons/ha). This study is an eye opener that much more carbon-dioxide could be sequestered if more trees are planted or retained in our tertiary institutions. Therefore, retention and planting of tree species in our tertiary institution is recommended.
2
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Seasoning Characteristics and Potential uses of Eucalyptus pilularis, Eucalyptus viminalis and Trichilia dregeana lumber tree species

100%
Kaba G., Desalegn G.
World News of Natural Sciences
|
2020
|
vol. 29
|
issue 3
162-178
EN
Technical information on lumber seasoning, moisture content (MC), density, mechanical, workability and chemical characteristics would strongly determine rational utilization of each lumber species. A study was conducted on home-grown two Eucalyptus species (Eucalyptus pilularis and Eucalyptus viminalis) and one indigenous (Trichilia dregeana) timbers with the main objective of determining some characteristics of lumber that will indicate quality and proper utilization. Study species were harvested from Shashemene, Asella and Arjo sites, respectively. The experimental design for seasoning and density was complete randomized design, a factorial experiment. The experiments were conducted using air and kiln seasoning methods. To determine initial moisture content oven drying method was used. The mean initial MC for the three timber species were 48.25%, 56.1% and 65.45%, respectively. The species were classified as very rapid seasoning rate during kiln seasoning. The mean shrinkage values were Tangential (6.31, 4.94 and 4.43%), radial (3.4, 4.02 and 2.10%) volumetric (9.46, 8.6 and 6.37%), when they seasoned from green to 12% MC, respectively. Seasoning defects such as cup, bow, crook, end split, surface and end-checks were observed, though the extent varies with species. The density of E. pilulalris, E. viminalis and T. dregeana at 12% MC was 780, 810 and 530 Kg/m3, respectively. The one-way analysis of variance indicated that there was significant difference (P>0.001) in initial MC, final MC, density values at different MC and shrinkage characteristics. They revealed good lumber characteristics and qualities, comparable with many indigenous and home-grown exotic timber species in density, seasoning rate and shrinkage. The tree species have to be well managed, properly harvested and sawn. Boards have to be properly stacked and seasoned to about 12% MC, with kiln and air seasoning methods that can help to minimize seasoning time, seasoning defects, shrinkage characteristics and increase quality.
3
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Seasoning technologies of Gmelina arborea Roxb. lumber species grown at Bonga, SNNP, Ethiopia

100%
Desalegn G., Kaba G., Tesfaye A., Amanuel S.
World News of Natural Sciences
|
2020
|
vol. 29
|
issue 3
269-281
EN
Quality and performance of wood and wood-based products have been seriously affected by the major factors, among which moisture content (MC), inappropriate drying (seasoning) and density are the preceding ones. A study was conducted on Gmelina arborea lumber with the main objective of determining some imperative seasoning and density characteristics of the lumber that will help determine its wood quality and decide proper utilization. Gmelina arborea logs were harvested from Bonga trial site of Central Ethiopian Environment and Forest Research Center (CEE-FRC). The experimental design for seasoning and density was complete randomized design. The experiments were conducted in air and kiln seasoning methods. Mean initial moisture content (IMC) of samples were determined using oven and MC for air seasoning stack was 143.80%, while for kiln seasoning was 120.19%. The final MC to reach to about 12% MC in air took 210 days, while kiln seasoning took 13.5 days. Kiln seasoning rate of Gmelina arborea lumber was 15 times faster than air seasoning. The species was classified as slow and fairly rapid air and kiln seasoning lumber species, respectively. When Gmelina arborea lumber seasoned from green to 12% MC, mean shrinkage (%) characteristic values: Tangential (3.63%), radial 1.58%), and volumetric (5.11 %). Mean density of Gmelina arborea lumber species at green (initial), basic and oven dried and at 12% MC was 940,400, 430 and 420 kg/m3, respectively. The density at 12% MC, (420 kg/m3) classified as light density lumber species. Gmelinaarboreashown good quality lumber characteristics, comparable with many indigenous and homegrown exotic lumber species in density, seasoning rate and shrinkage characteristics.
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