Oladele Falade | University of Ibadan Nigeria (original) (raw)

Papers by Oladele Falade

American Journal of Agriculture and Forestry

Open Journal of Forestry

Tree communities contribute to maintenance of species diversity in tropical forests. Coexistence ... more Tree communities contribute to maintenance of species diversity in tropical forests. Coexistence of many tree species is not without competition. Therefore, coexistence of tree species and size diversities occur sequentially or simultaneously in tropical natural forests. Understanding coexistence and How to cite this paper: Falade, O. F.

International Journal of Agriculture and Forestry, 2022

Spatial species diversity and size inequality contribute to maintenance of tree species diversity... more 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.

The 2nd International Electronic Conference on Forests—Sustainable Forests: Ecology, Management, Products and Trade

International Journal of Biodiversity and Conservation, 2020

Predicting carbon distribution of soil aggregates is difficult due to complexity in organo-minera... more Predicting carbon distribution of soil aggregates is difficult due to complexity in organo-mineral formation. This limits global warming mitigation through soil carbon sequestration. Therefore, knowledge of land use effect on carbon stabilization requires quantification of soil mineral cations. The study was conducted to quantify carbon and base cations on soil mineral fractions in Natural Forest, Plantation Forest and Farm Land. Five 0.09 ha were demarcated alternately along 500 m long transect with an interval of 50 m in Natural Forest (NF), Plantation Forest (PF) and Farm Land (FL). Soil samples were collected with soil cores at 0-15, 15-30 and 30-45 cm depths in each plot. Soil core samples were oven-dried at 105°C and soil bulk densities were computed. Sample (100 g) of each soil core was separated into ＞2.0, 2.0-1.0, 1.0-0.5, 0.5-0.05 and ＜0.05 mm aggregates using dry sieve procedure and proportion determined. Carbon concentration of soil aggregates was determined using Loss-on-ignition method. Mineral fractions of soil depths were obtained using dispersion, sequential extraction and sedimentation methods of composite soil samples and sieved into ＜0.05 and ＞0.05 mm fractions. Cation exchange capacity of two mineral fractions was measured using spectrophotometry method. Data collected were analysed using descriptive and ANOVA at 0.05. Silt and sand particle size decreased while clay increased with increase in soil depth in NF and PF. Subsoil depth contained highest carbon stock in the PF. Carbon concentration increased with decrease in aggregate size in soil depths of NF and FL. Micro-(1-0.5, 0.5-0.05 and ＜0.05 mm) and macro-aggregates (＞2.0 and 2-1.0 mm) were saturated with soil carbon in NF and FL, respectively. Cation exchange capacity of ＜0.05 mm was higher than ＞0.05 mm in soil depths of PF and FL. Fine silt (＜0.05 mm) determine the cation exchange capacity in soil depths. Land use and mineral size influence the carbon and cation exchange capacity of Gambari Forest Reserve.

The 1st International Electronic Conference on Forests—Forests for a Better Future: Sustainability, Innovation, Interdisciplinarity, 2020

Journal of Forest and Environmental Science, 2021

Nigerian Journal of Agriculture, Food and Environment, 2019

Tree stems are major above-ground carbon pools in the tropical forest structure. Forest structure... more Tree stems are major above-ground carbon pools in the tropical forest structure. Forest structure creates micro-climatic conditions for various ecosystem services. Natural and man-made disturbances cause changes in forest structure. However, the effect of forest structure dynamics on stem carbon sequestration is yet to be clarified in Gambari Natural Forest Reserve, Oyo State, Nigeria. Understanding influence forest structure dynamics on stem carbon could improve prediction of carbon sequestration potential of Gambari Natural Forest Reserve. Therefore, the aim of this study was to quantify forest structure and stem carbon stocks in Gambari Natural Forest Reserve. Ten sample (30m×30m 2) plots were randomly demarcated in Gambari Natural Forest using stratified random sampling method comprising 5 sample plots in each identified canopy structures; closed and open. Tree stems ≥10cm diameter-at-breast-height (dbh) were identified, enumerated and species diversity indices computed. Total height (TH) and diameter were also measured for volume and carbon estimation. Data collected were analyzed using descriptive statistics and ANOVA α0.05. A total of 50 tree species representing 25 families were identified in Gambari Natural Forest Reserve and closed canopy had higher diversity indices than open canopy structure. The lower and middle canopy class had the highest stems/ha in both structures. Diameter distribution of closed and open structure expressed extended reverse J-shaped and rotated sigmoid curves, respectively. Tree stem carbon stock were 0.66Mg/ha and 0.436Mg/ha in closed and open canopy structure, respectively. Microphyla pterigota (12.11%) and Triplochiton scleroxylon (25.84%) contributed highest carbon stock in closed and open canopy structures, respectively. The study concludes that the closed canopy structure of Gambari Natural Forest Reserve offers good option for carbon sequestration strategies as its structure and tree composition influences its stem carbon stock. However, only few tree species contributed to the high stem carbon stock in the study area. Therefore, these tree species can be considered in the establishment of carbon credit for carbon sequestration in Nigeria.

Nigerian Journal of Agriculture, Food and Environment, 2017

Soil and tree biomass are reservoir for carbon but there is uncertainty regarding their influence... more Soil and tree biomass are reservoir for carbon but there is uncertainty regarding their influence on soil carbon stabilization. Carbon associated with clay size aggregate is considered a major determinant of soil carbon accumulation. However, other aggregates are becoming relevant in the estimation of soil carbon accumulation. These limit the detail carbon estimation of soil. Therefore, soil carbon accumulation of aggregate sizes was estimated at two soil depths in Tectona grandis plantation. Six (30 x 30m 2) plots were randomly demarcated in the plantation and 360 topsoil and subsoil samples were used for this study. Soil core samples were collected at five points at depths of 0-15, 15-30 cm in each plot for period of six months. Soil core samples collected were oven dried at 105 0 C. Soil sample (100g) from each core sample was sieved into >2.0, 2.0-1.0, 1.0-0.5, 0.5-0.050 and <0.050 mm aggregate sizes using dry sieve procedure and proportions weighed. A subsample of 10g of each fraction was combusted in Muffle furnace at 500 0 C for 4 hours and carbon content estimated. Carbon content of the bulk soil was also determined. Data were analysed using descriptive statistics, regression analysis at α0.05 The 0.5-0.05 mm fraction had the highest proportion of soil at top and subsoil (39 and 28%, respectively). Aggregate size of <0.05 mm had the highest soil carbon concentration at topsoil and subsoil. Exponential and logistic equations performed better on the basis of R 2 , F-value and Standard Error of Estimate. Therefore, carbon content of 0.5-0.05 and 1.0-0.5 mm aggregates accurately estimate carbon content of topsoil and subsoil using the exponential equation. Carbon content of fine silt size aggregate (0.5-0.05 mm) determined carbon accumulated. Exponential model of soil carbon is determined by the aggregate size distribution of each soil layer.

Nigerian Journal of Ecology, 2017

Osun-Osogbo Sacred Grove in Nigeria is one of the major biodiversity hotspots in sub-Saharan Afri... more Osun-Osogbo Sacred Grove in Nigeria is one of the major biodiversity hotspots in sub-Saharan Africa with high plant diversity that has suffered considerable human-induced disturbance in the recent times. Therefore, this study aimed to quantify the canopy species diversity and regeneration pattern in the Sacred Grove. Three (0.09ha) plots were sampled in each identified forest type (old-growth, secondary-regrowth, and riparian forests) for the inventory of tree / sapling stems, and nested quadrats (5 x 5m 2) for seedlings. All stems enumerated were identified to species level. Data on diameter-at-breast height (dbh) and number of individuals per species were collected by plot. The patterns of tree (dbh ≥ 10 cm) distribution and regenerating (dbh ≤ 10 cm) population were examined using Detrended Correspondence Analysis (DCA) while the regeneration status of the grove was assessed by comparing the Importance Value Indices (IVI) of the current stocking and regenerating populations of the tree species. A total of 75 vascular species representing 66 genera and 30 families were identified. Fabaceae (13 spp), Apocynaceae (8 spp.), Euphorbaceae (7 spp.) and Rubiaceae (7 spp.) contributed 47.5% of the flora. The first two component axes of DCA (79.59%) delineated three community assemblages along disturbance gradient in the tree population. In addition, the first two component axes of DCA (107.70%) identified four communities along composition and disturbance gradients in the regenerating population. Analysis of IVI indicated that Dialium guineense (4.11), Funtumia elastic (6.08) and Cola millenii (5.06) were dominant and the most widely distributed tree species in the Grove. Osun Sacred Grove is rich in vascular species diversity with diameter distribution showing poor growth and inadequate self-replacement of emergent tree species. Gap creation and appropriate cultural practices should be undertaken to improve the regeneration of the emergent species.

Journal of Agricultural Research, 2011

The study investigated the use-efficiency of selected soil nutrient elements - Nitrogen (N), Pho... more The study investigated the use-efficiency of selected soil nutrient elements - Nitrogen (N),
Phosphorus (P) and Potassium (K) in the synthesis of dry matter by Tectona grandis (Linn.f.)
seedlings. T. grandis seedlings were grown on basement complex and ferric luvisol soils for 77
days after transplanting (DAT). Sixty polythene pots were filled with each soil type. Sixty soilseedling
samples formed an experimental unit that was replicated three times making a total of
360 seedlings. Eight seedlings were selected at intervals of 7 days for the first 28 DAT and four
seedlings for the remaining 42 DAT in each experimental unit. Composite samples of soil media
and seedlings were taken at intervals of 7 days and chemically analyzed. The dried shoot and
leaves were combusted at 500oC, for carbon content determination. Range of daily light
intensity during the experiment was 3.5 to 6.2 Klux while daily mean temperature was 24.7 to 27.5oC. Total carbon and biomass results showed that photosynthetic efficiency and photosynthetic carbon production of seedlings grown on basement complex were not significantly different from those of ferric luvisol. It is concluded that an increase in biomass could not be a major indicator of an increase in biomass carbon production. Therefore, photosynthetic efficiency alone may not be an adequate indicator of efficient photosynthetic carbon fixation. The root/shoot ratio was higher than 1.0 in both soils, indicating higher biomass allocations to the roots of the seedling. The study provides basis for the estimation of the phosphorus and nitrogen-supplying power of ferric luvisol and basement complex soils,

Conference Presentations by Oladele Falade

Environmental Sciences Proceedings, 2020

Tree size diversity is an indicator for biodiversity values of a forest. Microsite conditions of ... more Tree size diversity is an indicator for biodiversity values of a forest. Microsite conditions of forest determine the survival and growth of tree. 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, size distribution and spatial pattern of trees can identify the process governing resources utilization in the forest. The objective of the study was to investigate tree stems structural diversity of Elephant Camp natural forest in Omo Forest Reserve. Three and four 0.09ha sample plots were established in Riparian (RF) and Old-growth forests (OF) of Elephant camp, respectively. The tree stems (Dbh≥5cm) were identified to species level and enumerated within each plot and 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 Gini coefficient (GC), Coefficient of Variation (CV), H´ and I-D´. The performance of single two-and three-parameter Weibull models were evaluated; Kolmogorov-Smirnov (K-S) Chi-Square (χ 2), Root Mean Square Error (RMSE), Bias and Coefficient of determination (R 2). Data were analysed using descriptive statistics. A total of 27 and 24 tree species were identified in RF and OF, respectively. Stem density of RF was significantly higher than OF. The value of species diversity (H´, 1-D) and Evenness (E´) were higher in OF than RF while richness (Margalef and number of species) was higher in RF than OF. The Dbh were 38.30±21.4 and 42.87±19.2 cm in Riparian and Old-growth forests, respectively. Diameter distributions of both forests were positively skewed and expressed exponential pattern. The forest types of Elephant Camp natural forest comprise the same size frequency shape but different proportion of tree sizes and structural diversities.