Browsing by Author "Falade, O. F."

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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.
Cations of soil minerals and carbon stabilization of three land use types in Gambari Forest Reserve, Nigeria
(Institute of Forest Science, Kangwon National University, 2021) Falade, O. F.; Rufai, S. O.
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.
Critical factors in willingness to participate in forest management: tiie case of Gamiiari Forest Reserve, Oyo state, Nigeria.
(Forestry Association of Nigeria and the Department of Forest Resources Management, University of Ibadan, 2003) Jimoh, S. O.; Falade, O. F.
The study investigated the factors that could motivate members of forest adjoining communities to participate in the management of Onigambari Forest Reserve, Oyo State, Nigeria. Stratified quota sampling was used to select one hundred and fifty- eight respondents among the local community members. Data processing was by simple statistics, chi-square test of independence and logistic regression analysis. Results indicate that application of financial incentives does not have significant, effect on willingness to participate (p > 0.05), but the effects of non-financial), incentives and sociological factors are significant (p < 0.05). Results of logistic regression show that age, educational Status; incentive requirement (technical) and roles played in forest management have significant impact on willingness to participate in forest management will a log likelihood ratio of 278.317 (X(2) tab.= 124.342: df.= l38 and P= 0.05) . In view of the fact that socio-economic factors such as age; education; incentive requirement. tennurial rights, marketability of forest products and forest protection technics have significant effect on willingness to participate; it is recommended that government should embark on massive awareness campaign to educate the people on the benefits they stand to derive by actively participating in forest management. The practice of latmgya should be encouraged in order to motivate landless strangers to participate in forest regeneration. The forest reserve should be managed to supply multiplicity of goods and Services for: Social acceptability and ecological sustainability. Community Associations should be encouraged to establish nurseries from which timber takers would be required to purchase seedlings for replacing felled trees.
Determinant of carbon stabilization in tropical soils: a review of carbon sequestration potential of soil aggregate fractions
(Forestry Association of Nigeria, 2018-03) Falade, O. F.
Soils contribute to global climate mitigation through Sequestration of carbon. Soils that remain undisturbed for long period of time could be the best choice for carbon Sequestration. Quality of organic matter, land management practices and land use types had been considered the major factors influencing accumulation and stabilization of carbon associated with soil aggregate fractions. This understanding had limited the efforts at tracking carbon accumulation and stabilization of various aggregate fractions. However, other factors are becoming relevant in the evaluation carbon stabilization potential of various soil aggregate fraction in different soil texture and types. Therefore these factors require detail description. Organic and inorganic carbon compounds contribute to the soil carbon stabilization and subsequently, enhance carbon Sequestration. Understanding of the critical factors that control stabilization of carbon in soil aggregate fractions is limited. This limits the efforts on how to optimize carbon Sequestration potential among soil aggregate fractions and soil types and consequently, one of the reasons for unabated evolve of greenhouse gases from soils to the atmosphere. Therefore, brief description of factors that influence and optimize the Sequestration of carbon in tropical soils were reviewed. Hence, quantity and quality of organic matter, availability of basic cations; proportion of fine particle fraction in the soil; land management practices Option; organic and inorganic carbon concentration and soil moisture content were identified as the major factors influencing the soil carbon stabilization in tropical soils. The processes involve in carbon stabilization of tropical soils could be classified into Chemical and physical protecting mechanisms. Organic compounds derive from plant origin enhance soil particle aggregation while cations facilitate organo-mineral formation among soil fine particles. Surface area specificity is essential facilitator of organo- mineral formation among soil fine particles.
Early growth and dry matter yield of gmelina arborea (roxb) on basement complex and ferric luvisol soils
(The Forestry Association of Nigeria, 2009-12) Falade, O. F.; Bada, S. O.
The study investigated the use efficiency of selected soil nutrient elements-N, P and K in the synthesis of organic matter by Gmelina arborea seedlings. Gmelina arborea (family: Verbamacaea) seedlings were grown on basement complex and ferric luvisol soils for 3-months. Sixty polythene pots were filled with each soil type, which formed an experimental unit. Each experimental unit was replicated three times making a total of 360 Gmelina arborea seedlings. Eight seedlings were selected weekly for the first four weeks and four seedings per week for the remaining six weeks in each experimental unit. Composite samples of soil media and sampled seedling were taken weekly and chemically analyzed for the determination of possible changes in nutrient concentrations. The dried leaves and shoot were combusted at 500°c, for carbon content determination. Student t-test shows no significant difference in biomass carbon between basement complex and ferric luvisol soils (paired sampled t-test, 80.92 vs 80.35g/kg, respectively, p<0.05, n=10). Significant relationship exists between leaf area ratio (LAR) and leaf weight ratio (LWR) of seedlings grown on both soil types. Thus, P and N provide a much sensitive measure of the relative cost of dry matter production than potassium in these soils. The study highlights quantitative relationships that would allow silviculturists to estimate accurately the phosphorus and nitrogen-supplying power of basement complex and ferric luvisol soils.
Forest structure and carbon stocks of Osun-Osogbo sacred grove, Nigeria
(Academic Journals, 2020-03) Falade, O. F.; Taiwo, A. J.; Falade, O. F.; Iheke, J. U.
Forest trees and soil are considered for climate change mitigation. Forest structure of the grove is required to predict its capacity to mitigate climate change. Therefore, the objective of this study was to determine the forest structure and carbon stocks of Osun-Osogbo Sacred grove. Five (30 × 30 m2) plots were demarcated in Old-growth forest (OF) and Re-growth forest (RF). Trees with ≥10 cm diameter-at-breast-height (dbh) were identified to species level and enumerated. Tree height and dbh were measured and stem volumes were converted to carbon stock. Soil samples were collected with cores at three soil depths, oven-dried and carbon content estimated. The tree species diversity and richness indices of OF was higher than OR. Diameter distribution of OF and RF expressed reverse J-shaped and rotated sigmoid curves, respectively. The stem carbon stock ranged from 0.12±0.00 (OF) to 0.02±0.00 Mg/ha (RF). The soil carbon stock ranged from 0.65 (OF) to 0.90 Mg/ha (RF). Stand structure of OF was more develop than RF. The OF and RF contained high stem and soil carbon stocks, respectively. Forest structure enhances stem carbon stock of Old-growth forest while soil of Re-growth forest is also an option for carbon sequestration.
Forest structure and tree stem carbon stock of Gambari Natural Forest Reserve, Oyo state, Nigeria
(Faculty of Agriculture, University of Uyo, 2019-06) Falade, O. F.; Aderemi, S. A.
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×30m2) 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.
Nutrient-use efficiency of tectona grandis (Linn. f.) seedlings on basement complex and ferric luvisol soils of Ibadan, Nigeria
(Agricultural Research Council of Nigeria, 2011) Falade, O. F.; Oyeleye, B.
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 soil seedling 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,
Quantification of soil aggregate carbon in tectona grandis (Linn. f) plantation at University of Ibadan, Ibadan, Nigeria
(Forestry Association of Nigeria, 2016-12) Falade, O. F.
Forest soils are important reservoir for carbon and contribute to global climate mitigation. Fine clay size aggregate is considered a major determinant of soil carbon distribution. Other aggregate sizes are also important in carbon distribution and estimation. Therefore, soil carbon accumulation of aggregate sizes was quantified at two soil depths in Tectona grandis plantation. Six (30 x 30m') plots were randomly demarcated in the plantation and 360 topsoil and subsoil samples were used for this study. Soil core samples were collected at 4 comers and centre of each plot to depths of0-15,15-30 cm in each plot for period of five months. Soil core samples were oven dried at 105 °C. Soil bulk density and moisture content were estimated from the core samples. Soil sample (100g) from each core sample was sieved into >2,2-1,1-0.5,0.5-0.050 and <0.050 mm aggregate size fractions using dry sieve procedure and proportions estimated. Sub-sample (10g) of each fraction was combusted in Muffle furnace at 500 °C for at least 4 hours and carbon content estimated. Carbon concentration of the bulk soil was also determined. Data were analysed using descriptive statistics and ANOVA at a0 05 Bulk density ranged from 1.08 to 1.33 and 1.39 to 1.54 g/cm3 for subsoil and topsoil, respectively. Soil moisture content ranged from 17.23 to 23.36 and 14.08 to 22.15 cm for topsoil and subsoil, respectively. The 0.5-0.05 mm fraction had the highest values at top and subsoils (39 and 28% of the soil by weight, respectively) followed by 1 -0.5mm size fraction (27% of the soil by weight) at the topsoil and >2mm fraction (27% of the soil by weight) at the subsoil. Topsoil and subsoil had approximately the same proportion of 2-1mm and <50µm fractions. Fine silt (<0.05mm) fraction had the highest soil carbon concentration followed by sand size fraction (>2.0mm) and silt-size fraction (2-lmm) in topsoil and (0.5-0.05mm) in subsoil. The soil carbon associated with <0.05mm was greater than the >2mm fractions. The coefficient of Variation of carbon content were higher among the aggregates of subsoil than topsoil. The mean values of carbon content of bulk soil in topsoil were high than subsoil. Carbon concentration of fine silt size aggregate (0.5-0.05 mm) accurately estimate carbon content of topsoil and subsoil. Moisture content of the bulk soil influence carbon concentration of aggregate size of 1 mm and 0.05.
Role of traditional institutions in conservation of plant diversity
(Forestry Association of Nigeria, 2010-10) Falade, O. F.; Bada, S. O.
Plant diversity is the vast variety of plant life and its ecological complexities existing in any region. Circumstances gave rise to diverse experiences among indigenous societies about plant wealth around them. Plants are integral for the survival of the traditional culture. Each community has a unique set of social institutions. Conservation efforts can be more efficient if it is based on deep knowledge of social institutions. Plant diversity Conservation thrive if synchronizes with improvement in human welfare. It is imperative that plant diversity Conservation and its sustainability should focus traditional institutions because of its voluntary compliance features and cost effectiveness. This review focuses on critical factors in traditional Institution that can affect Conservation of plant diversity. These factors include local attitude, land use change, indigenous knowledge, religious belief, and cultural traditions.
Soil aggregates and carbon distribution in tectona grandis (linn. f.) plantation, Nigeria
(2017-12) Falade, O. F.
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 30m2) 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 0C. 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 0C 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 R2, 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.
Soil carbon distribution in three land uses of Gambari Forest Reserve Area, Oyo State
(University of Ibadan, Faculty of Agriculture and Forestry, 2019) Falade, O. F.; Adeagbo, A. A.
Soil adsorptive property is considered for mitigation of climate change in the terrestrial ecosystem. However, there are inconsistent findings on the contribution of aggregate sizes to carbon sequestration in soil depths. Inappropriate land-use practices cause increasing greenhouse gases in the atmosphere. Detail estimation of carbon associated with soil aggregates in different land-uses is required to identify land-use practice that promotes carbon accumulation. Therefore, the objective of the study was to investigate distribution of organic carbon associated with the soil aggregate sizes in selected land-uses. Three (30 m x 30 m) sample plots were established randomly in each of Natural Forest (NF), Plantation Forest (PF) and Cultivated Land (CL). Soil core samples were collected at 0-15, 15-30 and 30-45 cm depths using steel soil corers). Soil core samples were oven-dried at 105°C and bulk densities were computed. Oven-dried soil sample of 100 g was separated into five aggregates (>2, 2-1, 1-0.5, 0.5-0.05 and <0.05 mm) using the dry sieve procedure. Each aggregate (10 g) was heated in Muffle furnace at 500oC for 4 hours for soil carbon estimation. Aggregate sizes >2mm dominated NF and PL while 0.05 mm dominated CL. There was no significant difference in the distribution of aggregate sizes of NF and CL, except PL. The three land-use practices have the same proportion of aggregate 1-0.5mm at topsoil. Macro- and micro-aggregates influence soil carbon content in natural forest and plantation forest, respectively. Depth and land-use change caused re-distribution of carbon on soil aggregate sizes.
Some of the mechanisms for coexistence of tree species diversity in tropical forests: a review of effects of tree density dependence
(Scientific Research Publishing, 2023-01) Falade, O. F.
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 competition mechanisms of tree species requires knowledge of interactions within and between species. However, many conservation efforts and strategies failed due to inability to identify and maintain functional coexistence mechanisms among tree species in the forest. Also, most trees died because of pressure on their habitats and not because of limiting growth resources. Hence, species identity, minimum distance and size of the neighbouring trees which are responsible for coexistence of competing trees in most tropical forests have not been explicitly reviewed. Therefore, this review evaluated some of the density dependent mechanisms for coexistence of tree species alpha diversity in tropical forests. Many interactive mechanisms are responsible for coexistence tree species in tropical forests. Inter- and intra-specific competitions are the most significant and both facilitate positive and negative density dependence. Therefore, switching from negative to positive density dependence may occur in some situations. Positive and negative density effects regulate species abundance and coexistence through conspecific and heterospecific structures. Aggregates of conspecific and heterospecific neighbours constitute forest spatial structure. Negative density interactions are mutually exclusive and basically ranged from effect of species identity of neighbours, distance to neighbours and tree size of the neighbours to reference trees in the community structures. Some mechanisms shorten distances for heterospecific than conspecific interactions. Conspecific structures improved survival and growth of rare tree species. Interactive mechanisms in tree community and population structures facilitate species diversity and size inequality, respectively.
Spatial structure of neighbourhoods of small and large trees in Gambari Natural Forest Reserve, Nigeria
(Department of Forestry and Natural Environmental Management, Faculty of Agriculture, University of Uyo, Nigeria, 2025-03) Falade, O. F.
Structure of forest is spatially and temporally dynamic and therefore, effective prediction of structural diversity is difficulty. Correlation between spatial species diversity and size inequality regulates structure of tree community. Hence, estimation of tree structure around small and large tree sizes will provide understanding on process regulating tree distribution in Gambari Natural Forest Reserve. Therefore, the study was designed to investigate neighbourhood structure of small and large trees in Gambari Natural Forest Reserve, Oyo State. Two parallel line transects ranged 800 m to 1km long separated by 50 m were demarcated in Gambari Natural Forest Reserve. At least, four (30m x 30m) sample plots were established systematically on each transect. Minimum and Maximum DBH stems were selected at the centre of the plots, designated as Small and Large reference trees, respectively. A circular subplot (radius=10m; 314.2m2) was established around reference tree. Trees with diameter at breast height (DBH) ≥5 cm were enumerated, identified to species level, and DBH and their distances to reference tree were measured in each subplot. The species diversity indices of trees in each subplot were computed. Data collected were analysed using Descriptive statistics, Clark and Evans index. Species mingling and Diameter differentiation indices at α0.05. A total of 26 and 21 tree species was identified in the subplots of Large and Small reference trees, respectively. The species diversity indices (H´=3.0, 1-D =0.94 and M=6.24) around Large reference trees were higher than (H´=2.69, 1-D=0.91 and M = 4.99) of Small reference trees. Strombosia pustulata and Hildegardia barteri, and Strombosia pustulata and Triplochiton scleroxylon were the dominant tree species around Large and Small reference trees, respectively. Hundred percent (100%) and (55.56%) of subplots of Large and Small reference trees expressed regular pattern at 10m distance. The proportion of heterospecifics of Large reference trees was higher than Small at highest mingling value. Smallest DBH trees were less than 50% and 40% size around Large and Small reference trees, respectively. Trees with smallest DBH were less than 50% and 40% tree size around most of Large and Small reference trees, respectively. Neighbourhood of Large reference trees exhibited structural heterogeneity than Small reference trees.
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.
Tree size structure of tectona grandis (Linn f.) stand in hilltop and valley-bottom of Omo Forest Reserve
(MDPI, 2022) Falade, O. F.; Oguntona, S. B.
Variability of a microsite contributes to the size hierarchy in tree populations. Tree size symmetry varies with the available growth resources. However, competition hierarchy may not cause size symmetry in tree populations. The identification of mechanisms that determine size hierarchy has ecological significance in the management of a forest stand. Therefore, this study investigated the tree size structure of the Teak stand in the Hilltop and Valley-Bottom stands of the Omo Forest Reserve. A ten-year-old Teak plantation was delineated into Hilltop and Valley-Bottom stands based on topography. Five (30m x 30m) sample plots were systematically demarcated on 1 km transects in each stand. Tree stems with diameter at breast height (dbh) ≥ 10 cm were enumerated. Diameter at breast height and total height were measured using Girth tape and Spiegel Relaskop. Stem size inequality, diversity and stand attributes of both stands were evaluated for diameter and height. Data collected were analyzed using descriptive, correlation, regression analysis and t-test at α 0.05. Mean dbh and height in the Valley-Bottom stand (11.30 ± 4.82 cm dbh and 7.26 ± 3.21 m) were not significantly different from the Hilltop stand (10.19 ± 4.62 cm dbh and 7.12 ± 3.88 m). Stem density in the Hilltop stand (1431.0 stems/ha) was higher than in Valley-Bottom stand (1248.0 stems/ha). All distributions expressed unimodality, except the diameter distribution of the Valley-Bottom stand, which expressed bimodality. The inequality was strongly correlated with the diversity indices in dbh and height distributions in the Hilltop and Valley-Bottom stands, respectively. The same mechanism was responsible for the dbh and height structures of the Hilltop and Valley-Bottom stands, respectively. However, different mechanisms were responsible for the dbh and height structures of the Valley-Bottom and Hilltop stands, respectively.
Tree species and size diversity of Akure Strict Nature Reserve, Nigeria
(Science Publishing Group, 2023) Falade, O. F.; Aruwajoye, D. A.
Size and species structures control the natural mechanisms maintaining high structural diversity. Use of size inequality and species diversity measures singly for conservation decisions brings about inconsistent results. Therefore, most conservation efforts fail due to lack of understanding of mechanisms promoting coexistence of tree species. However, relationship between size inequality and species diversity indicates the natural mechanism promoting coexistence of high species diversity. Therefore, this study investigated the relationship between tree size inequality and species diversity in Akure Strict Nature Reserve. Eighteen and twelve plots (30m x 30m) were laid on parallel transects of 3.60km long and 50m width in Old-growth and Riparian forests, respectively. Trees with diameter-at-breast-height (dbh) ≥ 10cm were counted and identified to species level. Tree diameter at base, middle and top and total height were measured using girth tape and Relaskop. Tree species diversity (Shannon-Weiner; Simpson; Margalef indices) and dbh inequality measures (Gini coefficient, Gini; Coefficient of Variation, CV; Skewness Coefficient, Skewness) were computed and compared. Stem biomass were computed and converted to carbon stock. Data were analysed using descriptive, and correlation analysis at α0.05. Fifty-five (56) tree species representing 17 families were found in the forest. Species diversity indices were higher in Riparian while size inequalities in Old-growth forests. GC correlate with Shannon-Weiner (r=0.54; n=18, p≤0.018) and Margalef (r=0.473; n=18, p≤0.04) in Old-growth while GC correlate with CV (r=0.716; n=12, p≤0.09) in Riparian forests. The size inequality measures were strongly related with each other in Riparian while species and size inequality measures were strongly related with each other in Old-growth forests. The carbon stocks of Old-growth and Riparian forests were 117.21Mg/ha and 43.47Mg/ha, respectively. Triplochiton scleroxylon and Bridelia micrantha contained highest carbon stock in Old-growth and Riparian forests, respectively. Asymmetric mode of interaction in the absence of competition shows competition for below-ground resource, especially presence of moisture and nutrient gradient. Size inequality among different and within the same species determined coexistence tree communities in Old-growth and Riparian forests of Akure Strict Nature Reserve, respectively.
Tree species coexistence and diversity on elevation gradient of elephant camp natural forest, Nigeria
(Scientific and Academic Publishing, 2022) Falade, O. F.; Babalola, T. D.
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.
Vascular plant diversity and carbon stocks of selected sacred groves in Southwestern, Nigeria
(Faculty of Agriculture, University of Uyo, Akwa Ibom State, Nigeria, 2025-03) Falade, O. F.
Sacred groves are hotspot areas for tree species diversity and rare woody plants. Tree species composition have not been evaluated for its contribution to carbon in sacred groves. This study was designed to investigate influence of stand structure on variation of biomass and soil carbon stocks in the selected sacred sites in Southwestern, Nigeria. Ten (0.09ha) plots were randomly demarcated in each sacred grove. Tree ≥5cm Diameter-at-Breast Height (DBH) were identified and species diversity indices (Shannon-Weinner, H´; Simpson, 1-D) were computed. Total height (TH) and DBH were measured for volume and carbon estimation. Soil samples were collected with cores at three depths in each plot. Core samples were oven-dried at 105°C and 100g of soil was separated into >2.0, 2.0-1.0, 1.0-0.5, 0.5-0.05 and <0.05mm aggregates and carbon proportion determined. Data were analysed using descriptive statistics and ANOVA. A total of 28 tree species representing 18 families, 23 tree species representing 14 families, 8 tree species representing 6 families and 16 tree species representing 12 families were identified in Ori-Oke, Bilikisu-Sugbo, Olumo rock and Osun-Osogbo groves, respectively. The H´ ranged from 2.61 (Ori-Oke) to 1.67 (Olumo-rock), while 1-D ranged from 0.94 (Bilikisu) to 0.74 (Olumo-rock). Biomass carbon ranged from 24240.00 (Bilikisu-Sugbo) to 7998.36 kg/ha (Ori-Oke). Carbon content increased with decrease in aggregate size in soil depths of Ori-Oke and Bilikisu-Sugbo while decreased with decrease in Olumo-Rock and Osun-Osogbo Groves. Bilikisu-Sugbo obtained the highest tree species diversity and carbon storage. Therefore, Bilikisu-Sugbo should be considered for plant diversity and carbon storage conservation schemes.
Woody plant population, dynamics and regeneration in tropical dry forest formations
(Zenith BookHouse Ltd., Ibadan, 2021) Falade, O. F.