Omo Biosphere Reserve Research Articles

Effects of canopy structure on the diversity and structure of tree species in omo biosphere reserve, Ogun state, Nigeria

This study assessed the effects of canopy structure on tree species diversity and forest structure in OmoBiosphere Reserve. Landsat imagery was used; supervised maximum likelihood classification was used to classify the reserve into two canopy structures (closed and open canopies). Random sampling technique was used to delineate 10 sample plots of 30m x 30m in each canopy type. Tree species with a diameter at breast height (Dbh) ≥10cm were enumerated in each sample plot. Shannon Weiner and Simpson’s indices were used to assess the tree diversity, while diameter and height stratification were used to evaluate the forest structure. Shannon Weiner and Simpson’s indices were 3.507 and 0.953, respectively, in open canopy structure (OCS) and 3.396 and 0.951, respectively, in closed canopy structure (CCS). Species richness and population were higher in OCS (64 and 575, respectively) than in CCS (56 and 531, respectively). Milletia thonningii andStrombosia pustulata were the dominant tree species in OCS and CCS, respectively. The mean Dbhand height in OCS were 40.09cm and 22.86 cm; and 50.21cm and 23.05cm in CCS, respectively. The basal area was 110.01m2/ha in OCS and 207.97m2/ha in CCS. The volume yield per hectare in OCS was 343.35m3/ha and 842.49m3/ha in CCS. The OCS was dominated by younger trees than the CCS. Canopy structure affects tree species richness, population, and diversity, as well as tree attributes.

Phytosociological Assessment and Diversity of Woody Species in Omo Biosphere Reserve, Nigeria

Les activités d’exploitation forestière, les changements et les variations climatiques menacent la durabilité de l’ensemble de l’écosystème forestier. L’entretien et l’évaluation périodique de divers écosystèmes sont donc cruciaux pour la survie à long terme des êtres humains. Cependant, les données de base sur l’appauvrissement des écosystèmes forestiers au Nigéria sont insuffisantes ou absentes. Le but de la présente étude était d’évaluer la relation phytosociologique entre la composition des espèces et la diversité des espèces ligneuses à la réserve de biosphère de l’Omo. Trois lignes de transect ont été coupées à 200 m de distance l’une de l’autre. Chaque transect comporte 4 parcelles de 50 x 50 m en alternance à 100 m d’intervalle. Les arbres avec e” 10 cm de diamètre à hauteur de poitrine (DHP) dans chaque parcelle ont été mesurés pour la hauteur, DHP. Les données ont été analysées pour la composition, la richesse, la diversité, la densité relative et la dominance relative des espèces, l’indice de valeur d’importance des espèces (IVI), la diversité des espèces a été calculée à l’aide des indices de diversité de Shannon Weaner et de Simpson. Les données ont été analysées à l’aide du logiciel PAST Version.3 et de Microsoft Excel 2010. Le coefficient de corrélation de Carl-Pearson a été calculé entre différents paramètres phytosociologiques. Un total de 427 arbres représentant 57 de 22 familles ont été rencontrés dans la réserve de biosphère de l’Omo. La densité de peuplement des espèces d’arbres dominantes/ha varie de 0,33 arbres/ha à 26,33 arbres/ha. Pour la similarité de Simpson entre les parcelles, elle variait de 0 % à 77 % pour toutes les parcelles. La diversité des espèces (indices de diversité de Simpson) entre les parcelles varie de 64 % à 93 % pour toutes les parcelles. En conclusion, cette étude démontre la promesse d’une approche in situ de la préservation de la nature. Logging activities, climate change and variation are threatening the sustainability of the entire forest ecosystem. Maintenance and periodic assessment of diverse ecosystems are, therefore, crucial for the long-term survival of human beings. However, baseline data on the resulting depletion of forest ecosystems in Nigeria are insufficient or lacking. The aim of the present study was to assess the phytosociological relationship between species composition and the diversity of woody species at Omo Biosphere Reserve. Three lines of transect were cut apart 200 m far from each other. Each transect has 4 plots of 50 x 50m in an alternate manner at 100m intervals. Trees with e” 10 cm diameter at breast height (DBH) in each plot were measured for height, DBH. The data were analyzed for species composition, richness, diversity, relative density, and relative dominance, Species Importance Value Index (IVI), Species diversity was computed using Shannon’s Weaner and Simpson’s diversity indices. The Data were analyzed using PAST software Version.3 and Microsoft Excel 2010. The Carl-Pearson correlation coefficient was calculated between various phytosociological parameters. A total of 427 trees representing 57 from 22 families were encountered in Omo Biosphere Reserve. The stocking density of dominant tree species/ha ranges from 0.33 trees/ha to 26.33 trees/ha. For Simpson’s similarity between the plots, it varied from 0 % to 77 % for all the plots. The species diversity (Simpson’s diversity indices) between the plots varies from 64 % to 93 % for all plots. In conclusion, this study demonstrates the promise of an in-situ approach to nature preservation.

Assessing local people's perceptions and preference for ecosystem services to support management plan in Omo Biosphere Reserve, Nigeria

Little attention has been given to local people's perception of and preferences for ES, especially in developing countries. Such disregard of local community's priorities for ecosystem services (ES) can lead to non-coherent development plans and minimise community participation in ES-based conservation. Therefore, this study conducted an ES assessment to understand how local people perceive the importance of ES and how they prioritise ES. A questionnaire survey was conducted among 302 residents in 65 enclaves of Omo Biosphere Reserve (OBR), Nigeria. Data analyses including logistic regression analysis and spatial analysis were carried out to explain the residents' responses to survey items. Respondents identified crops, fruits, water, firewood as the preferred ES. The explicit spatial maps showed a high priority for ES around the North-Western, Eastern and Southern region of the Reserve. Gender, age group, education level, income level and household size all played essential roles in the importance of ES. Income and household size were the only sociodemographic factors that influenced the willingness of the local people to conserve ES. This study could help to make an informed decision on the management of the resources and facilitate the provision of ES in the reserve. Thus, this research could contribute to the effective implementation of the Lima Action Plan (LAP) in OBR.

Geospatial modelling of Forest Canopy Density and Landscape Assessment in Omo Biosphere Reserve, South-western Nigeria

Forest has an important role in the global carbon cycle that covers over one-fourth of the world’s geographical area. It is one of the major natural resources and magnificent terrestrial ecosystems of the world. Forest Canopy Density (FCD) is imperative in the assessment of forest status and is a primary indicator of potential management interventions. Landsat images of 1990 and 2018 were used in this study. Remote Sensing has demonstrated to be very cost-effective in mapping and monitoring changes in forests, and other environmental issues. Forest cover change and fragmentation were analysed using FCD and Landscape metrics. The FCD was obtained from the combination of data from the Advance Vegetation Density Index (AVI), Bare Soil Index (BI), and Forest Shadow Index (FSI). Four categories of change were identified in the reserve, no change, growth, degradation and deforestation. There was no change in 222.57 ha (52.98%), growth had 81.54 ha (0.69%), degradation with 116.01 ha (27.61%) and deforestation with the least change with 0.81 ha (0.19%). Degradation with a change rate of 0.97% contributed more in terms of change. There is a slight increase in the values of the three diversity indices (SHDI, SHEI, SIDI) while a high degree of homogeneity is recorded in the no forest class and the three others classes were fragmented. Understanding the dynamics of the forests is important in mitigating climate change and support for biological resources.

Slenderness coefficient models for tree species in Omo biosphere reserve, South-western Nigeria

This study was carried out to aid the prediction of tree slenderness coefficient using non-linear regression models for tree species in Omo Biosphere Reserve, Southwestern Nigeria. Systematic line transect design was adopted for the study. Three transects were laid with four plots on each transect at alternate positions which made a total of 12 sample plots (50 m × 50 m) in the study area. Diameter at breast height (DBH), diameter at the top, diameter at the middle and diameter at the base as well as total height and merchantable height of all trees were measured. Descriptive statistics, Pearson’s correlation and regression analysis were adopted for the study. The study showed that about 23.5% of the trees in the study area are susceptible to wind-throw damage. Correlation analysis revealed that DBH is a better predictor of Slenderness coefficient than other tree growth characteristics. Six non-linear models were adopted for the tree slenderness coefficient prediction. The best models were selected based on the highest Adj.R2, lowest AIC and SEE values. Normal logarithmic equation SLC = 30.72 + (-41.21) In(D) was selected as the candidate model for the pooled data. The same candidate model (Natural logarithm) was selected for both the Desplatsia lutea and Strombosia pustulata species with the equation SLC = -0.04 + (-63.82) In(D) and SLC = 22.12 + (-51.40) In(D) respectively while exponential model with equation SLC = 170.94e(-1.93) was selected for Sterculia rhinopetala. These equations were recommended for predicting slenderness coefficient for each of the tree species in Omo Biosphere with apparently valid potentials for enhancing reasonable quantification of the stands’ stability.

Ecological and Structural Characteristics of Riparian Forest in Omo Biosphere Reserve

An investigation on the structural characteristics of the riparian forest in Omo Biosphere Reserve was carried out. The structure was analyzed through diameter class distribution, basal area and breast height. Riparian forest showed a major characteristic in the physiognomy of forests along major river, streams and Upland vegetation and the Core, Buffer and Transition zones that is highly variable in the diameter class distribution (reserve J type), Mean basal area per hectare for major river is 294,089.30 cm2/ ha, Stream 613.027 cm2/ha, and Upland 205,648 cm3/ha. Mean basal area for core is 507,399.50 cm2/ha, buffer had 340,699 cm2/ha and transition 264,656 cm2/ha. While mean volume per hectare for core is 7955.2 m3/ha, buffer 7260 m3/ha and Transition 6254.4 m3/ha. Maximum dbh of 246 cm was obtained in the core species. Many stands of riparian forests are facing various levels of structural and floristic simplification, which include fundamental transformations in vegetation physiognomy from dense stands to riparian scrub or bare land. 
 Keyword: Riparian forests, structure, diameter, basal area, species dominance, Omo

Carbon Stock and Storage Capacity of Tree Species in Strict Nature Reserve of Omo Biosphere Reserve, Ogun State, Nigeria

Carbon is the main casual factor for global warming and climate change. Increased industrialization is known to be the chief contributor to increased atmospheric carbon concentration. Forest ecosystem plays significant role as a major terrestrial carbon sinks that reduces atmospheric carbon concentration. This study assessed the amount of carbon sequestered in the Strict Nature Reserve (SNR) of Omo Biosphere Reserve and the contribution of individual tree species to the carbon stocks. A non-destructive approach was deployed in the study. Systematic random sampling technique was used to demarcate 20 sample plots of 30x30 m. In each sample plot, all tree species (DBH ≥ 10 cm) were identified and measured for their total heights while diameter were measured at breast height (DBH), base, medium and top. Findings indicated 616 stems/ha in the reserve, Strombosia pustulata (63stems/ha) had the highest tree population. Diversity indices showed that the reserve is rich in tree species diversity with potentials for incessant growth due to the existence of young trees in the lower canopy. The high biomass and carbon storage of the tree species revealed the contribution of the reserve to climate change mitigation through co2 absorption from the atmosphere. Ceiba pentandra (9stems/ha) contributed most (26.14%) to the entire carbon stock in the reserve. However higher stem density of tree species hectare-1 did not translate to higher percentage of carbon stock input of the tree species to the entire carbon stock of the reserve. Trees with higher DBH and wood density store more carbon than trees with lesser DBH and wood density. Thus, tree species ability to sequester more carbon is dependent on its DBH and wood density, rather than its population. The need to conserve and increase the tree species diversity is implicated in the study.

Detecting trade-offs, synergies and bundles among ecosystem services demand using sociodemographic data in Omo Biosphere Reserve, Nigeria

The complexity of the relationships among multiple ecosystem services (ES) is not fully understood. This could be because of the difficulty in assessing ES relationships, in general, and particularly, an uneven study of geographical distribution and the relationships among ES demand remains under-researched. Yet, understanding relationships among multiple ES can support policy and management decisions, from problem definition to interventions. This novel research focused on addressing some of the challenges, presenting relationships among ES demand undertaken in Omo Biosphere Reserve (OBR), Nigeria, to improve understanding and extend the geographical coverage of ES relationship studies. In this study, primary data were obtained using a questionnaire survey administered to 302 individuals in OBR. Multinomial regression, correlation and factor analysis were used to identify key ES, explain the influence of sociodemographic attributes on ES preferences and identify the trade-offs, synergies and bundles of ES demand, respectively. The results showed that there were 18 key ES demanded with more preference for provisioning ES such as crops than other ES. Few sociodemographic attributes were identified to influence people’s preferences for ES. Furthermore, major trade-offs occurred between provisioning ES with synergies observed among provisioning, regulating and cultural ES. Of the six bundles identified, the first three bundles explained 53% of the total variance which involved environmental, health and basic needs. Our findings not only provide valuable information that could help achieve a well-managed landscape but also support decision-making process and management strategies that could potentially strengthen rural livelihoods.

Socioeconomic and Lifestyle Assessment of Selected Forest Based Communities in Omo Biosphere Reserve, Ogun State, Nigeria

This study assessed socio-economic characteristics and lifestyle of selected forest based communities in Omo Biosphere Reserve, Ogun state in southwest Nigeria. The study aim was to explore the influence of socioeconomic factors on their lifestyle, quality of life and implications for forest environment. A sample of 180 respondents from three enclaves was selected using simple random sampling. Data collected was analyzed using SPSS version 20 and presented as Tables and charts. The results showed that 86.11 per cent of them were adults between ages 31years and 70years who have families, responsibilities to cater for and have capacity to further expand their land into the forest. Only 2.2 per cent of the respondents have no formal education indicating a great decline in illiteracy. About 75.56 per cent have incomes ranging between 500,000 to 1,000,000 yearly. 58 per cent respondents have a household size ranging between 6-10 persons. 7.22 per cent have farm size less than 3 Ha while the rest have more up to 10 Ha. 83 per cent of the respondents were involved in cocoa farming while the remaining 17 per cent shared kola, palm and plantain crops farming. The type of constraints affecting the livelihood strategy often influences the mitigation measures undertaken by farmers in the study area. On health, malaria is the most prevalent disease experienced by 73.3 per cent respondents. However, the health care facilities are far from residents and also inadequate. As a result, about 95.6 per cent resorted to self-medication using herbs in case of illness. Younger and active age groups have their resultant socio-economic implications for forest environment but the obvious is its negativities in respect of exploiting more lands for farming hence, government should ensure increase awareness aimed at protecting the forest in order to prevent further forest encroachers. 
 Keywords: Socioeconomic, Lifestyle, Communities, Forest

Floristic composition, structure and diversity distribution in Omo Biosphere Reserve, Ogun State, Nigeria

Tree species composition and diversity were assessed in Omo Biosphere Reserve, Ogun State, Nigeria. Systematic sampling design was used to lay two straight line transects, each of 1000 m long and separated by 500m, in the reserve. Four Temporary Sample Plots (TSP) of size 50×50 m were laid along each transect at 250 m interval. Eight plots were enumerated for identification and frequency of occurrence (FO) of all woody plants with diameter at breast height (DBH) ≥10 cm. Identified tree species were categorised into different diameter classes. Data collected on DBH were used to compute Stem Volume (SV), Basal Area (BA) and Number of Trees per hectare (NT). Shannon Weiner and Simpson's indices were used to assess species diversity. Identified flora species in the reserve were from 30 families, 59 genera and 66 species. Family Ebenaceae had highest FO of 90±16.25/ha in the study area. The DBH of 146±0.72 cm3; SV of 0.47±0.86 m2 /ha; BA, 86.45±0.34 m /ha; and NT, 405±1.95 were recorded. Shannon Weiner and Simpson's indices obtained were 4.01 and 0.09 respectively indicating a moderately diverse area. This study provides a baseline for the management of the forest reserve in southwestern Nigeria.Keywords: Omo Biosphere Reserve, Species diversity, Species conservation, Tree density, Floristic composition

Density and Abundance of the Red-Capped Mangabey (Cercocebus Torquatus) In Omo Biosphere Reserve and Idanre Forest Reserve, South Western Nigeria

Density and Abundance of the Red-Capped Mangabey (Cercocebus Torquatus) In Omo Biosphere Reserve and Idanre Forest Reserve, South Western Nigeria

Modelling and Comparison of Above-Ground Tree Biomass of Omo Biosphere Reserve Using Field and Landsat 8 Data

Modelling and Comparison of Above-Ground Tree Biomass of Omo Biosphere Reserve Using Field and Landsat 8 Data

Land Use Change Detection in OMO Biosphere Reserve Using GIS and Remote Sensing

Inadequacy of reliable data on the rate and extent of forest conversion remains a major problem threatening sustainable forest management in Nigeria. In this study, we examined land use change pattern in Omo Biosphere Reserve, Nigeria, between 1987 and 2011. Landsat TM imagery for 1987 and Landsat ETM + imagery for 2011 were analyzed for land use change detection using Erdas Imagine 9.2 and ArcGIS 9.2. The results showed that farmlands, disturbed forests, settlements and rivers increased in area while the areas covered by the natural forests, plantations, and roads decreased from the 1987 figures. The farmlands had the highest increase in area (19025 hectares) from 1987 figures, followed by disturbed forests (10917 hectares), settlements (4262 hectares), and rivers (235 hectares). The highest reduction in area was observed for plantations (22699 hectares), followed by natural forest (10803 hectares) and roads (937 hectares). As at 1987, the natural forest was the most extensive land cover type, occupying 39.32% of the reserve. However, the disturbed forest is now the most extensive of all the land use types covering 36.34% of the reserve, followed by the natural forest (32.05%), farmland (14.78%), plantation (10.62%), settlement (4.11%), roads (1.22%), and rivers (0.87%). There was a drift in the abundance of the natural forest cover from the northeastern part of the reserve in 1987 to the northwestern part in 2011 due to unsustainable exploitation in the former and various conservation projects in the later. It is expected that the information provided in this study will aid decisions that will enhance sustainable management of the reserve.

Using Cultural Resources in Host Communities and the Environs to Enhance the Natural Resources Attractiveness of Ecotourism Development in Omo Biosphere Reserve (OBR), Nigeria

The study was undertaken to evaluate the cultural resources in Omo Biosphere Reserve (OBR) host communities and its environs that can enhance the attractiveness of ecotourism development which can ultimately lead to the sustainable development of the area. OBR is in waterside area of Ogun State, Nigeria. It is a UNESCO designated Man and Biosphere (MAB) site. OBR natural resources has been under threat of overexploitation in the last few decades and hence the need to sustainably conserve and protect these resources using ecotourism. Fauna direct sighting particularly the large mammals like the forest elephants (Loxodonta africana cyclotis), forest buffalo (Syncerus caffer nanus) and others have been rare although their presence have been established. Interview and direct observation methods were used to collect primary data. Data collected were analysed and presented in tables. The result showed that there were significant festivals in OBR environs that can attract visitors to OBR. The study identified the incorporation of festivals in the OBR as added attractiveness for the natural resources in OBR in its ecotourism development. Development of ecotourism will not only conserve the endangered fauna and flora species of Omo Biosphere Reserve but will also provide additional income and job opportunities for the communities and will equally ensure peaceful co-existence of the people.

Physico-chemical properties of topsoil under indigenous and exotic monoculture plantations in Omo biosphere reserve, Nigeria

Sustainable management of soil in plantations to a large extent depends on a thorough understanding of the trend and dynamics of soil properties under them. This study evaluated selected physico-chemical properties of topsoil under monoculture plantation of an indigenous tree species - Nauclea diderrichii, and those of four exotic tree species – Theobroma cacao, Gmelina arborea, Pinus caribaea and Tectona grandis, located in Omo Biosphere Reserve, Ogun State, Nigeria. Percentage sand, silt and clay did not vary significantly (p > 0.05) among monoculture plantations at the 0-5 cm depth while significant variations were observed at lower soil depths in some of the plantations. Iron, Zinc, Copper and Manganese varied significantly (p < 0.05) among monoculture plantations. Zinc and Copper were highest in Gmelina arborea Plantation at the 0-5cm depth, while Iron and Manganese were highest in Theobroma cacao and Nauclea diderrichii Plantations respectively at the same depth. Organic matter and total nitrogen varied significantly (p < 0.05) among plantations and were highest in Theobroma cacao, Tectona grandis and Nauclea diderrichii at the 0-5, 5-10 and 10-15cm depths respectively. Available phosphorus varied significantly (p < 0.05) among plantations and was highest in Nauclea diderrichii, Theobroma cacao and Gmelina arborea at the 0-5, 5-10 and 10-15cm depths respectively. Indices of change (%) based on average values of soil properties for the three sampled depths revealed a degradation of organic matter, total nitrogen, available phosphorus, potassium, sodium, iron, and pH in most of the exotic plantations, while calcium, zinc, copper and manganese improved except in Pinus caribaea plantation. The use of Nauclea diderrichii for plantation establishment and taungya farming in the reserve is recommended for soil conservation. Key Words: Monoculture, indigenous species, exotic species, Omo, soil properties

Aerobic Heterotrophic Bacterial and Fungal Communities in the Topsoil of Omo Biosphere Reserve in Southwestern Nigeria1

As a part of the surveillance effort to monitor the ecological status of Omo Biosphere Reserve in the southwestern region of Nigeria, the aerobic heterotrophic bacterial and fungal communities of the topsoil were investigated in March 1995 and April 1996, before the onset of the rainy season. Four distinct wood-tree plantations, a core strict nature reserve (SNR) area, and a buffer zone were sampled. The topsoil samples (7.5 cm depth), including the litter, were taken with an auger (8 cm diameter) and transported to the laboratory in polyethylene bags. One-gram dry weight equivalent of sample was suspended in 10 ml sterile water, and serial dilutions from it were used for the estimation of bacterial and fungal densities. The bacterial and fungal densities ranged in the order of 106 and 103 cfu/g, respectively. Out of the 18 bacterial and 16 fungal species that were obtained, 13 and 12, respectively, were isolated from the core SNR. About 46 to 69 percent of the bacteria and 50 to 83 percent of the fungi species found in the SNR were absent in different combinations in the plantations and the buffer zone; these variations were significant among the sites monitored. The bacterial and fungal species compositions were significantly different between the SNR and each of the other sites. Proportional distributions within the sites were significant only for the bacterial communities. It would appear that plantation and human activities have caused significant changes in the distribution and species richness of the heterotrophic bacterial and fungal communities relative to the undisturbed SNR area of the Omo Biosphere Reserve.

Aerobic Heterotrophic Bacterial and Fungal Communities in the Topsoil of Omo Biosphere Reserve in Southwestern Nigeria1

Aerobic Heterotrophic Bacterial and Fungal Communities in the Topsoil of Omo Biosphere Reserve in Southwestern Nigeria1