Scholarly works in Social and Environmental Forestry

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Comparison of Four Distribution Functions for Fitting Diameter in Second Rotation Tectona grandis Linn. f. Plantations in Eda Forest Reserve, Nigeria
(Forest and Forest Products Society, 2017) Alo, A.A.; Chukwu, O.; Ogunleye, B. C.
Tree diameter is a very important variable in forestry; its accurate description is vital to planning if the forest is to be managed in a sustainable manner. Probability density functions are widely used for characterizing tree diameter. However, there is limited information on the diameter distribution for most of plantation in the country especially in the study area. Therefore, this research assesses the performance and suitability of beta, 3-parameter gamma, 3-parameter lognormal and 3-parameter Weibull distribution functions for fitting diameter at breast height (Dbh) of the second rotation of Tectona grandis Linn.F plantation in Eda Forest Reserve, Nigeria. Sixteen (16) temporary sample plots, (each 20 m x 20 m) were randomly selected across four second rotation age series (7, 8, 10 and 11years), whose originalages were 24, 31, 32 and 37 respectively. The distribution functions were fitted using maximum likelihood estimators. The performance of each function was tested using the Kolmogorov-Smirnov (K-S) statistic, Anderson Darling test, Chi-square, mean absolute error (MAE) and mean square error (MSE). The test results revealedthat 3-Parameter Weibull distribution was the most suitable for characterising Dbh. Weibull distribution had the least Kolmogorov-Smirnov statistic (0.0453), Anderson Darling test (1.231), Chi-square (24.9700), mean absolute error (0.0964) and mean square error (2.1688). Therefore, 3-parameter Weibull distribution is the best and recommended for fitting Dbh of second rotation T. grandis species in the study area for sustainable teak timber management.
"Development of digital elevation model for Okomu National Park, Nigeria"
(TMKarpiński Publisher, 2018) Chukwu, O.; Alo, A. A.; Ezenwenyi, J. U.
The type of soil, fauna and flora species that are found in an environment is affected by the elevation characteristics of the land. However, the ability to provide techniques and model that will effectively explain the elevation patterns of protected areas will aid sustainable management of the forest and its resources. This study developed Digital Elevation Model (DEM) for Okomu National Park, Nigeria. Point coordinates (2,272) with their respective elevations were randomly obtained covering the entire study area. Interpolated natural neighbor algorithm of the Quantum Geographic Information System was used to generate Digital Elevation Model for the National Park from the elevation data. Topographic map was extracted from the DEM at an interval of 10 m from one another. It was observed that the elevation in the study area ranged from 19 m to 105 m with an average of 56.32 m above sea level. Hence, the parkland is regarded as a gentle slope. This study revealed that the study area is not prone to flood or runoff due to its gentle slope nature. Therefore, this study is recommended as baseline information for ecological management as well as guide in the development of conservation strategies for flora and fauna species in the study area.
Development of Information System for Wood-Based Industries in Ekiti State, Nigeria.
(Integrated Publishing Association and Academic Science Publications and Distributions, 2017) Alo, A. A.
Development of information system in forestry sector is crucial in order to manage resources in a sustainable manner. Spatial distribution of forest and wood-based industries is important for sustainability. However, geographic location and other information about the wood-based industries in Ekiti state, which can provide baseline information for investors in wood industry, are dearth. To proffer solution to this, information system was developed for wood-based industries in the State using geographic information system. This was done by taking the coordinates and photographs of all wood-based industries in the State. Types of equipment used for different wood conversion were assessed with the aim of determining their strength and capacity. The photographs and coordinates were loaded into ArcView GIS for analysis. The wood-based industries were represented on the State map using their coordinates while respective pictures were hotlinked appropriately. Various local governments in the State were represented with polygons of different sizes and wood industries were represented with points. The results obtained from the analysis were used to produce database in MS SQL server. The database created by Microsoft SQL server formed the data access (back end) of the software developed using C# Programming Language. Appropriate codes were written at the business logic layer for both the back and the front ends. The software was developed in an Interactive Development Environment (IDE) using visual studio. It was observed that most of the wood-based industries were concentrated at the southern part of the State where there were more forest reserves. Gbonyin Local Government has the highest number of wood industry (46) while Efon Local Government has none at all. Over 95% of the existing wood industry was functioning with 91% of them using CD6 machine. The software developed is user-friendly, facilitates efficient data storage and prompt information retrieval, adequate and has provision for regular updates.
Equations for estimating bark thickness of Gmelina arborea (ROXB) trees in Omo forest reserve, Nigeria
(Ministry of Agriculture and Livestock Development, Nepal, 2018) Alo, A.A.; Ogana, F.N.
The measurement of bark thickness is an important factor for computing inside bark volume of a standing tree or log. Bark thickness at breast height can easily be measured. However, when bark thickness at relative height of a standing tree is required, the application of equations becomes imperative. In this study, equations were developed for estimating bark thickness at relative height and at breast height. Stratified random sampling was used to establish 50 sample plots of 0.04 ha size across 10 age series in the Gmelina arborea plantation in Omo Forest Reserve, Nigeria. Eight equations for estimating bark thickness as function of diameter inside bark (dib) and Relative Bark Thickness (RBT) were developed. Equation was also developed for predicting absolute bark thickness at breast height. The equations were assess based on Root Mean Square Error (RMSE), Mean Absolute Bias (MAB), Akaike Information Criterion (AIC) and Shapiro-Wilk test of normality. The results showed that six out of the nine equations performed relatively well in estimating bark thickness. The best equation for estimating bark thickness as function of dib had RMSE, MAB and AIC values of 0.065, 0.049 and -125.989, respectively. The best equation for RBT had 0.109, 0.079 and -75.577, respectively. The equation for absolute bark thickness at breast height had 0.204, 0.152 and -12.697. The equations did not violate the assumption of normality as revealed by normality test (p > 0.05). With these equations, any analytic volume equation can be used to compute the inside bark volume of the standing trees. The relative back thickness and diameter inside back functions developed in this study were found to be satisfactory based on the various criteria used for their assessment. Thus, they are recommended for use in estimating the back thickness and diameter inside bark of Gmelina arborea stands in similar ecosystem.
Forest Cover Dynamics of a Lowland Rainforest in Southwestern Nigeria Using GIS and Remote Sensing Techniques
(Scientific Research Publishing, 2021) Oluwajuwon1, T. V.; Alo A. A.; Ogana, F. N.; Adekugbe, O. A.
The rate of forest degradation and deforestation in Nigeria has been increasing over the years and is prominent in the southwestern parts. Despite the significant change and degradation observed in a lowland rainforest in the region—Ogbese Forest Reserve, there is a great dearth of information about the level of forest cover change. Therefore, this study determined the cover dynamics of the rainforest reserve over the epoch of 20 years using Geographic Information System and remote sensing techniques. Coordinates of the boundary and some other benchmark places within the forest reserve were obtained. Secondary data collection included: Landsat imageries of 1998, 2002 and 2018. An interview guide was used to obtain information from forest officials and locals of the surrounding communities to complement the spatial data obtained. Image classification was done using the maximum likelihood algorithm. The rate of change across the epochs was determined using the area of the land cover classes. The level of vegetation disturbance in the reserve was determined through Normalized Difference Vegetation Index. Five different forest cover classes were identified in the study area: forest, plantation, farmland, grassland, and bare land. The natural forest reduced significantly from 34.43 km2 (48%) in 1998 to 8.73 km2 (12%) in 2002 and was depleted further by 2018, while other cover classes increased. NDVI value also reduced from 0.25 to 0.13. Agriculture, among others, was observed as the main driver of forest degradation and deforestation in Ogbese Forest Reserve. The study concluded that the remaining forest (i.e. plantation) could also be depleted by 2025, as it decreases by −0.94 km2 per year if proper reforestation and management practices are not introduced.
Geospatial modeling of forest landscape assessment: a case study from Ikere forest reserve
(African Journal of Open Libraries (AJOL)., 2020) Chukwuka A. F.; Alo A. A.; Aigbokhan, O. J.
This study set out to assess the dynamic characteristics of the Ikere forest reserve landscape between 1985 and 2017 using remote sensing data and spatial metrics. Landscape of the study area maintained complex patterns of spatial heterogeneity over the years. Forest cover loss to other land cover types results in new large non-forest area at increasing rate. As at the year 2017, the changes in land cover types were not yet at equilibrium, thus the need to determine the future forest cover extent using a three-way markov Chain model. The decrease in number of patches of forest land (NumP) with increase in its mean patch size (MPS) shows that the forest is becoming a single unit probably due to clearing of existing patches of forest trees. The decrease in class diversity and evenness (SDI and SEI) of the general landscape over the years strengthens this assertion. The findings of this study would be very helpful to government and other stakeholders responsible for ensuring sustainable forest and general environment.
Human Settlements Interactions and Deforestation in Gambari Forest Reserve located in Oluyole Local Government Area (LGA) of Oyo State, Nigeria
(The University of Port Harcourt, 2021) Agbor, C. F.; Alo, A. A.; Aigbokhan, O.J .
This study was designed to examine changes in land cover types and the interaction of human settlements with the forest and impact of such interaction on the reserve. Community leaders and randomly selected community dwellers in each of the selected settlements were sampled for group discussion to obtain information on population and services of the forest that attract them to the reserve. Landsat images of 1984 and 2019 were used to extract land cover types using maximum likelihood classifier in Idrisi environment. The level of attractiveness and Interactions of the communities with the reserve were determined employing gravitational model. Results show that there was an increase in the size and number of settlements within the study area and decrease in in forest cover by 34% and 6.02% respectively. It was also revealed from the study that about 39% of the total area was taken over by development (building, roads and other classes) within the forest reserve, while 3% of the developed area gave way to forest cover. The degraded parts of the reserve in recent time was about 16% of the total reserve area and about 78% remained forest cover. From the results it is obvious that the level of interaction and imparts of such interaction depends on the community’s population size rather than distance. It is therefore imperative to regulate the activities of adjoining communities and those within the Gambari forest reserve by appropriate authorities.
Modeling Urban Green Space Dynamics and Associated Proximate Drivers in Ibadan Metropolis, Ibadan, Nigeria
(Forest and Forest Products Society, 2018) Alo, A.A.; Nwatu, J. U.
However, there is dearth of information on the dynamic of UGS caused by proximate drivers (PD) in Ibadan metropolis of Oyo State, Nigeria having flooded the direct drivers. Therefore, this study was designed to assess UGS changes and the PD that contribute to the changes in the last 34 years. Landsat images of 1984 (TM), 2001 (ETM+) and 2018 (OLI), coordinates of bench mark places of Ibadan metropolis were obtained. Geometric correction and principal component analysis were carried out on the satellite images. Land cover classification was achieved using maximum likelihood classifier method. Shapefile of Ibadan metropolis was super imposed on the classified images for land use/land cover assessment and Kappa statistics was used to carry out accuracy assessment on the image classification. The change detection analysis was carried out on the classified images using geometric geoalgorithm of ArcGIS. Urban green space change (dependent variable) and Proximate Distance (distance from; UGS edges, roads, built-up area and elevation) were extracted from the Landsat images using the distance command in IDRISI with Cramer's V test of association analysis. Four land use/land cover categories were identified; urban green space, built-up, water body and bare-soil. The UGS and water body decreased from 126,344 ha (85.36%) and 233.01ha (0.16%) to 100,481.20 ha (67.88%) and 136.17ha (0.09%) respectively from 1984 to 2018. On the other hand, builtup area and bare-soil increased from 9,250.72 ha (6.25%) and 12,193 ha (8.23%) to 32,227.16 ha (21.77%) and 15,176.20 ha (10.25%) respectively from 1984 to 2018. Distance from built-up (0.59) and UGS edges (0.56) are the dominant PD of UGS dynamics. About 25,863 ha of green space at rate of 760 ha per annum is given up to built-up area and bare-soil between 1984 and 2018. Urban green space decreased with increase in built-up area. The dominant proximate drivers influencing the changes were the distance from the built-up area and urban green space edges.
Modelling forest cover dynamics in Shasha forest reserve, Osun state, Nigeria
(Faculty of Agriculture, Usmanu Danfodiyo, Sokoto, Nigeria, 2020) Alo A.A.; Adetola, A.A.; Agbor, C.F.
Understanding the dynamics of forest cover change is vital to forest manager for planning, formulation of policies and decision making. Nigeria’s forest reserves have witnessed significant changes over the years due to various anthropogenic activities. Incessant activities of poachers, illegal fellers and other farming activities in Shasha Forest Reserve have adverse effects on the ecosystem with consequence for global warming. However, there is no up-to-date information on the dynamics of forest cover in Shasha Forest Reserve. Therefore, this study aimed at assessing forest cover changes using remote sensing in Shasha Forest Reserve. Landsat Thematic mapper (TM), Enhanced Thematic Mapper (ETM+) and Operational Land Imager (OLI) data for the periods of 1984, 2000 and 2017 were obtained. The Landsat images were pre-processed and classified using maximum likelihood classification algorithm. The Classification was based on Anderson scheme of land use/cover for change detection between 1984 and 2017. Kappa coefficient was used for accuracy assessment. The future pattern of forest cover changes for 2034 was forecast using the Multi-Layer Perception (MLP) Markov chain model in IDRISI. Three land cover classes were identified: Built up, Shrubs and Forest land. Built up and Shrubs increased at an annual rate of 0.09% and 0.18% respectively and forest decreased at an annual rate of 0.27% between 1984 and 2017. Large area of forest land has been converted to built-up and shrubs with no significant replacement from 2000 till date. The forest was projected to decrease between 2017 till 2034 at the rate of 0.15% per annum.
"Spatial Distribution of Colleges of Education and Effects on the Forest Ecosystem: A Case Study of College of Education Ikere, Nigeria"
(Timeline Publication Pvt. Ltd., 2014) Alo, A.A.; Aturamu, O.
Distribution of various Colleges of Education in Nigeria was examined. The list of Colleges of Education in the country was obtained from National Commission for Colleges of Education (NCCE) and their respective coordinates were obtained. Satellite imagery of Ikere forest reserve was obtained from Google earth while the sketch map was obtained from Ekiti State Department of Forestry (ESDF). Photographs of some parts of the forest reserve were taken. A set of 50 questionnaire was administered by the old staff of the College of Education, Ikere – Ekiti. The coordinates of various Colleges of Education obtained were loaded into ArcGIS to represent their locations on the map of Nigeria. Federal Colleges were represented with points, state colleges were represented with asterisks while private colleges were represented with upward arrows. All the attribute data obtained for Ikere forest reserve were used to generate a digital map showing the extent of all the various land use within the forest ecosystem. Various forest types were represented with polygons of different shapes and colours. Roads of different types were represented with lines of different sizes. Photographs of some parts of the forest reserves were hotlinked to reveal the actual status on the land. Administered questionnaire was coded and analyzed appropriately. It was discovered that the Colleges of Education established by the State Government were more (56.63%) than those established by the Federal Government (26.51%) while the private ownership established the least Colleges of Education (16.87%) in the country. When the spatial distribution of Colleges of Education by geopolitical zones were examined, South-West recorded the highest number (21.69%), followed by North-East (20.48%), South South (15.66%), North Central (14.46%), in that order and the least was recorded in South-East (13.25%). Forest in its natural status in Ikere forest reserve have been reduced to mere farmland, degraded land and encroached plantation of Gmelina arborea and Tectona grandis, which was not the case before the inception of the College. Old staff of College of Education Ikere Ekiti was responsible for the level of depletion of the forest reserve.
"Spatial Distribution of Forest Reserves and Sawmills in Oyo State, Nigeria"
(Forest and Forest Products Society, 2017) Alo, A. A.
Geographic Information System (GIS) is a veritable tool for spatial analysis in forestry. The proximity to forest reserves has been considered one of the major factors affecting the spatial distribution of wood-based industries. However, information on number of sawmills and spatial distribution of both the forest reserves and sawmill in Oyo Sate is lacking. Hence, this study employed GIS to develop spatial distribution map of forest reserves and sawmills in Oyo State, Nigeria. The secondary data used in this study included sketch maps and high-resolution satellite imagery of all the forest reserves in Oyo State as well as the shapefile of the State. The primary data included the coordinates of locations of all the sawmills’ location in all the four forestry zones (Ibadan, Oyo, Shaki and Ogbomosho) in the state and coordinates of some bench-mark places within each forest reserve that could easily be identified on ground. Interview guide was used to obtain information on factors responsible for the location of each sawmill. The sketch maps were georeferenced using the coordinates of the bench-mark places and the area covered by forest reserves were digitized. This was superimposed on the satellite imageries and also vectorized. The coordinates of sawmill locations were used to develop spatial distribution map for the sawmills. The shapefile of forest reserves and the point coordinates of the sawmills were superimposed on the shapefile of Oyo State in layers to produce a spatial distribution prediction surface for both the forest reserves and the sawmills in the study area. The mean distance from each sawmill to the forest was determined. This procedure was used to obtain Average Transport Distance (ATD) for local government and finally for forestry zones. It was observed that forest reserves in Oyo State covered a total of 342,461 ha of land which accounted for 12.92% of the total land area of the state. Opara forest reserve recorded the highest area of land (248,640 ha), accounting for about 72.60% of the total land area of forest reserves in the state while the least was Olokemeji forest reserve (75.11 ha), accounting for about 0.02%. About 135 sawmills were recorded in all the forestry zones in Oyo State. Sawmills in Oyo forestry zone is significantly higher than Ibadan zone. ATD was highest in Ibadan forestry zones (12.55 km) with corresponding lowest percentage (3.70 %) of sawmills. Oyo Forestry Zone accounted for about 56.30 % of the total number of sawmills in the state with the least ATD of 4.02 km. Availability of electricity and nearness to source of raw material favoured sawmills location in Oyo and Shaki forestry zones. Spatial distribution of sawmills was more influenced by constant supply of electricity and nearness to free forest areas than the presence of forest reserves.
Spatio-Temporal Dynamics of Urban Green Space and Temperature in Ado-Ekiti Metropolis, Nigeria
(Forests and Forest Products Journal, 20, pp.40-53, 2020) Okikiola M. A.; Alo A. A.
The Nexus between the Urban Green Space (UGS) and Land Surface Temperature (LST) helps to formulate policy for sustainable management of UGS where there is an urban sprawl like Ado Ekiti. However, there is a dearth of information on UGS and LST in Ado-Ekiti. Therefore, this study adopted remote sensing and geographic information system techniques to determine the dynamics and nexus between UGS and LST as well as investigating the perceived factors responsible for the UGS changes in Ado-Ekiti metropolis, Nigeria with a view to providing relevant information for sustainable management of the UGS and mitigating the Urban Heat Island. Landsat imageries of 1987 (TM), 1998 (ETM) and 2019 (OLI) were obtained. Map of Ado-Ekiti was georeferenced and digitized to obtain its shapefile. The maximum likelihood algorithm of supervised classification in ArcGIS was used to classify Landsat imageries. The shapefile was superimposed on the classified imageries and clipped for the determination of land use land cover sizes. The LST was extracted from the imageries by converting the digital numbers to the surface temperature. Correlation analysis was used to determine the nexus between the UGS and LST. Four land use land cover: green spaces, built-up area, water bodies and bare land, were identified in the Ado-Ekiti metropolis. The UGS decreased from 74.4% in 1987 to 38.7% in 2019. Similarly, water bodies reduced from 0.9% in 1987 to 0.1% in 2019 respectively. However, built-up area and bare land increased from 21.9% and 2.9% in 1987 to 51.1% and 10.5% in 2019 respectively. The LST in Ado-Ekiti metropolis increased from 22.1°C in 1987 to 30.5 °C in 2019 respectively. The Built-up area and bare land had the highest LST values compared with UGS and water body in all the years. The relationship between the UGS dynamics and LST was negatively correlated with r2 ranging from -0.51 to -0.83. By the year 2049, the vegetation would have reduced to 36.0% while built-up and bare land would have increased to 52.4%. on the other hand, water with no significant change.
Taper equations for Gmelina arborea in Omo forest reserve, southwestern Nigeria
(School of Agriculture and Agricultural Technology (SAAT), Federal University of Technology, Akure (FUTA), Nigeria, 2011) Alo, A.A.; Aturamu, O.; Akindele, S. O.
Taper equations were generated for five diameter classes and four age series (11, 16, 21, and 26-year-old) in melina arborea plantations in Omo forest reserve, Nigeria. Three temporary sample plots of 20 m x 20 m were randomly selected from each age series. The diameter at the breast height (dbh) of all trees within each sample plot was measured and grouped into five dbh classes of 10–20 cm, 20–30 cm, 30–40 cm, 40–50 cm and 50 cm and above. The tree whose dbh was closest to the mean dbh of each diameter class was selected for further enumeration and felling. Before felling, the following measurements were made on each selected tree: diameter at the ground level (DG), diameters at 15 cm (D15), 30 cm (D30), and 45 cm (D45) above the ground and total height. After felling, the stump height (Hst) was measured and the log was sectioned into bolts after which the inside-back and outside-bark diameter of each bolt as well as the length were measured. Taper functions were then developed for each diameter class and age series. The taper function for the diameter classes were: , , , , for trees in 10–20 cm , 20–30 cm, 30 -40 cm, 40–50 cm and 50 cm and above diameter classes, respectively. The functions generated were assessed using F-ratio, Root Mean Square of Error (RMSE) and adjusted R-square (R2adj). The models were validated using t-test to compare the observed and predicted values. The taper functions generated in this study were found to be satisfactory based on the various criteria used for their assessment and validation. Thus, they are recommended for use in estimating the taper of Gmelina arborea trees.
Temperature variability and impact of vegetation cover in Ibadan metropolis, Ibadan, Nigeria
(Faculty of Agriculture, Usmanu Danfodiyo University, Sokoto, Nigeria, 2021) Nwatu, U. J.; Alo A. A.; Agbor, C. F.
This study evaluates the changes in Urban Green Spaces (UGS) and the impact of such changes on surface temperature in Ibadan Metropolis between 1984 and 2018 using Landsat images. Digital numbers of the imageries were converted to physical quantities, radiance, and brightness temperature, while the temperature retrieval from thermal channels of Landsat imagery was carried out and the derived surface temperature validation was done through near-surface air temperature. This was followed by the reclassification of the images using Normalized Difference Vegetation Index (NDVI) as a proxy for vegetation cover and was regressed with urban temperature to observe their nexus, which explains the ability of UGS to absorb solar radiation in the study area. The land use land cover maps of the metropolis were developed from green, red and near-infrared channels of Landsat data in Idrisi software environment using maximum likelihood classifier. Results show that the mean temperature of Ibadan metropolis increased from 33.29℃ to 35.76℃ over 34 years, and the temperature of different land cover types considered in this study revealed that built-up and bare soil areas recorded the highest temperature changes compared to other land cover types (green spaces and water body). Also, the correlation analysis between UGS and ST showed a strong negative relationship with R2 values ranging from -0.71 to -0.89. The study, therefore, concludes that the relationship is strong enough to ascertain that urban vegetation cover has the capacity to mitigate climate change effects. The increase in temperature may contribute to the variations in surface temperature, thus giving rise to the urban heat island effect. The study revealed the efficiency of geospatial techniques in data capturing for reliable information on sustainable management of urban green spaces.
The Use of Forest Inventory in Estimating Illegally Felled Trees of Tectonagrandis Plantation in Agudu Forest Reserve,Lafia, Nasarawa State, Nigeria
(Redshine Publication, 2019) Egbewole Z. T.; Rotowa O. J.; Alo, A. A.; Ojo A. S.; Oluwasanmi T. D.; Enenche J. A.; Oluwaseesin, M. B
The aim of this study is to evaluate the Use of Forest Inventory in Estimating Illegally Felled Trees of Tectonagrandis Plantation in Agudu Forest Reserve. Seven (7)plots were randomly selected from different area of the whole plantation. Perimeter measurement for each plot were; Permanent Sample Plot 1 (PSP1) to (PSP3) and Temporary Sample Plot 4 (TSP4) to Temporary Sample Plot 7(TSP7) with size 30m by 30m each totaling 0.63ha. Six (6) mean trees in respect of girth class and height class and 1 plus tree were identified and the stumps of felled trees were measured in each of the 7plots. The study was laid out in a 7 x 6 x 6 factorial experiment in a Randomized Complete Block Design (RCBD) with a total of 252 treatment combinations in order to facilitate the interpretation of the main and the evolving interaction effect. Treatments were analyzed with respect to 7 Sample plots, 6 girth classes and 6 height classes. It was observed that a total of 640 Teak stand and 250 stumps of felled trees on 7plots of size 30m by 30m each totaling 0.63ha.The average tree height was 14.56m, average merchantable height was 11.56m, total basal area (BA) for the 7plots was 48.15m2 and the mean BA was 0.08m2. Total tree Volume (using Newton’s fomular) was 147.69m3 and the mean volume/tree was 0.23m3. The average stump girth (SG) was 30.54cm, 0.09m2 Stump Basal area, the estimated mean tree height was 14.34m while the average Estimated Stump Volume (ESvol) was 0.62m3. The Total Stump Basal area for the whole 250 felled tree stumps was 21.44m2 on the 0.63ha sampled plots, this will amount to 34.03m2/ha while the Total Estimated Stump Volume (ESvol) was 154.18m3 on 0.63ha sampled plots, this will amount to 244.73m3/ha. Based on ‘International prices for teak: Historical and current, and price forecasts’ the World Market Price of Teak as at 2018 is put at 1221.31USD/m3at N355/USD, this will amount to (N433565.1/m3x 244.73m3/ha x 161.28ha) the sum of N17,112,838,083.00 equivalent to a total loss of about (48,205,177.70USD)of felled Teakat 2018 year ending.Comparing all the models tried in this study using the fit statistics, model2: ESV = -0.26 – 1.71BD + 11.38BAs + 0.03MeanTHp ……………….Eq23.With basal diameter (BD), Basal area and mean Tree Height as the independent variables which had (R2 = 99.80, SEE = 0.02, with a negative intercept of -0.26) is the most appropriate prediction model. For predicting tree stump volume of Teak in Agudu Forest Reserve, the 5 ranked models are considered fit because they meet the basic requirement of a good fit model having negative intercept whereas the rest model with positive intercept may be discarded. The stand volume equations, which incorporated various tree growth variables, will enhance future yield prediction of the trees in the study areas since they provide quantitative basis for estimating stand growth parameters. It is believed that these models and volume prediction equations will enhance sound and informed management decisions and conservation measures for the remaining Tectonagr and is stands.
"Yields and nutrient pools in soils cultivated with Tectona grandis and Gmelina arborea in Nigerian rainforest ecosystem"
(King Saud University, 2011) Adekunle, V.A.J.; Alo, A.A.; Adekayode, F.O.
This study examined the yield of the two most prominent exotic species in southwest Nigeria and the nutrient status of soils cultivated with these species. The impacts of plantation development on soil nutrients were also examined. The plantations species are Gmelina arborea (Gmelina) stands established in 1984, 1988, 1990 and 1994 and Tectona grandis (Teak) established in 1990, 1992, 1994, 1996 and 1997. Growth data and composite soil samples from 3 depths (0–15, 15–30 and 30–60 cm) were collected from five equal sized plots (20 • 20 m2) randomly located in the plantation of the two species. Also, soil samples were collected from the adjacent natural forest for comparison. The results for both species show that tree growth variables increased substantially with increase in tree age. There was significant difference in number of trees per hectare, dominant diameter, volume/ha and MAI for the Gmelina stands. In the Teak stand, there was significant difference in most of the tree growth variables also. Nutrients required by plants to survive were present in the soil samples from the plantations and the natural forest in different proportions. There was high correlation between percentage sand and most of the tree growth variables for both species. The pH value obtained for the Gmelina stands ranged between 6.47 and 7.47 while that of Teak stands ranged between 5.57 and 8.33. There was also a high and positive relationship between