Tree Species and Size Diversity of Akure Strict Nature Reserve, Nigeria (original) (raw)
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International Journal of Agriculture and Forestry, 2022
Spatial species diversity and size inequality contribute to maintenance of tree species diversity in tropical forests. Coexistence of tree species requires interactions within and between spatial species and size diversity. However, elevation gradient has significant impact on growth and species interactions. Failure of most conservation efforts is due to inability to identify and maintain coexistence mechanisms existing in the forest. Understanding the contribution of elevation gradient to coexistence of tree species will improve conservation efforts and terrestrial carbon budgeting. Therefore, association between tree diversity and size inequality on elevation gradient of Elephant Camp Natural Forest was investigated. Eight (30m x 30m) plots were systematically demarcated on 1km line transects in each identified elevation (Hilltop and Valley-Bottom stands). Trees diameter-at-breast height (dbh) were enumerated and identified to species level. Tree dbh was measured and density estimated. Tree species diversity (Shannon-Weiner, Simpson and Margalef indices) and size inequality (Gini coefficient, skewness and Coefficient of variation) were computed. Stem volume and biomass were computed and converted to biomass carbon. Data collected were analysed using descriptive, correlation analysis and principal component analysis. Tree density varied from 435/ha to 767/ha. There was positive correlation between Skewness and Gini coefficient in Hilltop stand and negative correlation between Skewness and Simpson index in Valley-Bottom stand. The measures of tree size inequality and species diversity were strongly associated with each other in Valley-Bottom stand and not in Hilltop stand. Structural diversity and species diversity determined the competitive interaction among tree communities in Hilltop and Valley-Bottom stands, respectively.
Diversity and Volume Assessment of Tree Species in the Tropical Forest at Obanla, Akure, Nigeria
Asian Journal of Research in Agriculture and Forestry , 2020
This study focused on the assessment of tree species diversity and abundance at The Federal University of Technology, Akure Tropical Forest Obanla. The research was carried out from May, 2019 to September, 2019. Complete enumeration sampling was adopted for the data collection and all trees with diameter at breast height (Dbh) above 0.1 m were identified and measured. Other tree growth variables, such as diameter at the base (db), diameter at the middle (dm), diameter at the top (dt) and the total height were all measured for volume estimation. Ricinodendron heudelotii Hd the highest number of stems (13), so it was the dominant tree species.The result shows that mean tree volume ranges from a minimum of 0.26 m 3 for Olalaceae family, to a maximum of 77.70 m 3 for Euphorbiaceae family. Ceiba pentandra of Malvaceae family had the highest mean volume (14.62 m 2) while the lowest was recorded for both Khaya senegalensis and Newbouldia laevis with a volume of 0.13 m 2. The family of Euphorbiaceae was regarded as the dominant family in the natural forest with 26 tree species which is the highest in this study and with the highest volume (77.70 m 2). Shannon Wiener diversity index and species equitability index according to Pielou's of 3.24 Original Research Article Olawoyin et al.; AJRAF, 5(4): 11-19, 2020; Article no.AJRAF.56230 12 and 0.92 were respectively obtained for the study area. This study revealed the efficacy of an undisturbed natural forest in in situ conservation. Active regeneration can be carried out for proper stocking of the forest so has to make it a potential biodiversity hotspot.
2020
This study was designed to determine tree species composition, vegetation structure and the potentials of these protected forests for in-situ biodiversity conservation. The study areas were stratified into two different forest types (primary forest and sacred forest). Data were collected from eight 25m plots situated in these four forest areas (Akure Strict Nature Reserve, Eda Forest Reserve, Osun Osogbo Sacred Grove and Igbo Olodumare Sacred Grove) all located in southwestern Nigeria using a simple random sampling method. The results showed that the forest ecosystem included 57 tropical hardwood species belonging to 29 families. The highest tree species, diversity index and species evenness were found at Osun Osogbo sacred grove. This followed closely by Akure primary forest and Eda primary forest while Igbo Olodumare sacred grove had the least species composition species diversity index and species evenness. These findings confirmed that both the primary forests and sacred grove f...