Social and Environmental Forestry

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Author: search.filters.author.Chukwu, O.End date: 2019

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    "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.
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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.