DEPARTMENT OF FOREST RESOURCES MANAGEMENT
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Item Structural diversity of tree stems of elephant camp natural forest in Omo Forest Reserve(MDPI, 2021) Falade, O. F.; Iheke, J. U.Tree size diversity is an indicator of biodiversity values of a forest. Microsite conditions of a forest determine the survival and growth of trees. However, the contribution of variable habitats to tree size hierarchy and segregation is poorly understood. Tree size variation in a population is caused by different competition mechanisms. Therefore, the size distribution and spatial pattern of trees can identify the process governing resource utilisation in the forest. The objective of the study was to investigate the tree stem structural diversity in the Elephant Camp natural forest in the Omo Forest Reserve. Three and four 0.09 ha sample plots were established in Riparian (RF) and Old-growth forests (OF) in the Elephant Camp natural forest, respectively. The tree stems (Dbh ≥ 5cm) were identified to the species level and enumerated within each plot, and the stem density was computed. The diameter at breast height (Dbh) was measured with diameter tape. Species diversity was assessed using Shannon–Weiner (H’) and Simpson indices (1-D’), while size inequality was assessed using the Gini coefficient (GC), coefficient of variation (CV), H’ and I-D’. The performance of single two- and three-parameter Weibull models was evaluated using Kolmogorov–Smirnov (K-S) chi-square (χ2), root-mean-square error (RMSE), bias and the coefficient of determination (R2). Data were analysed using descriptive statistics. A total of 27 and 24 tree species were identified in RF and OF, respectively. The stem density of RF was significantly higher than that of OF. The values of species diversity (H’, 1-D’) and evenness (E’) were higher in OF than in RF, while richness (Margalef and number of species) was higher in RF than in OF. The Dbh was 38.30 ± 21.4 and 42.87 ± 19.2 cm in Riparian and Old-growth forests, respectively. Size-density distributions of both forests were positively skewed and expressed exponential pattern. The forest types of the Elephant Camp natural forest comprise the same size-density frequency shape but a different proportion of tree sizes and structural diversities.Item Carbon fraction distribution of soil depths of Omo Biosphere Reserve, Nigeria(Forestry Association of Nigeria, 2019-10) Ubaekwe, R. E.; Falade, O. F.; Ariwaodo, J. O.Soil is regarded as largest carbon reservoir in terrestrial ecosystem but availability of Information on soil aggregates cum carbon fraction distribution along depths in relation to specified location is lacking. Soil carbon accumulation of aggregate sizes was estimated at five soil depths in natural forest reserve, Omo Biosphere Reserve, Nigeria. Guided by the heterogeneity of the reserve, it was stratified into close and open canopy structures. Fourteen and six (30m x 30m) sample plots were demarcated in close and open canopy, respectively. Profile pit was dug at the center of sample plots (30m x 30m) and soil samples were collected at 0 - 20, 20 - 40, 40 - 60, 60-80, 80 - 100cm depths and air dried. Air- dried soil samples (100g) were separated into five aggregate sizes (>2.0, 2-1, 1-0.5, 0.5-0.052mm, <0.052mm) using wet sieving method, and percentage carbon content of each aggregate fractions were determined using Loss on Ignition Method. Data collected were analyzed using descriptive statistics and ANOVA at α 0.05. Carbon distribution varied among the soil aggregates and across the depths. The degree of carbon protection and carbon stability are higher in <0.052mm aggregate size than in other aggregates. Macro-aggregate and micro-aggregate are responsible for carbon accumulation in surface and sub-surface soils, respectively. Therefore, macro-aggregate and micro-aggregate are responsible for carbon Sequestration in soil of Omo Biosphere Reserve.