Scholarly works in Social and Environmental Forestry

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Author: search.filters.author.Agbor, C. F.Has files: Yes

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    Spatial Distribution of Soil Moisture Content and Tree Volume Estimation in International Institute of Tropical Agriculture Forest, Ibadan, Nigeria
    (Scientific Research Publishing, 2022) Alo A. A.; Agbor, C. F.; Jebiwott, A.; Temiloluwa, O.
    The role of soil moisture in the survival and growth of trees cannot be overemphasized and it contributes to the net productivity of the forest. However, information on the spatial distribution of the soil moisture content regarding the tree volume in forest ecosystems especially in Nigeria is limited. Therefore, this study combined spatial and ground data to determine soil moisture distribution and tree volume in the International Institute of Tropical Agriculture (IITA) forest, Ibadan. Satellite images of 1989, 1999, 2009 and 2019 were obtained and processed using topographic and vegetation-based models to examine the soil moisture status of the forest. Satellite-based soil moisture obtained was validated with ground soil moisture data collected in 2019. Tree growth variables were obtained for tree volume computation using Newton’s formular. Forest soil moisture models employed in this study include Topographic Wetness Index (TWI), Temperature Dryness Vegetation Index (TDVI) and Modified Normalized Difference Wetness Index (MNDWI). Relationships between index-based and ground base Soil Moisture Content (SMC), as well as the correlation between soil moisture and tree volume, were examined. The study revealed strong relationships between tree volume and TDVI, SMC, TWI with R2 values of 0.91, 0.85, and 0.75, respectively. The regression values of 0.89 between in-situ soil data and TWI and 0.83 with TDVI ascertain the reliability of satellite data in soil moisture mapping. The decision of which index to apply between TWI and TDVI, therefore, depends on available data since both proved to be reliable. The TWI surface is considered to be a more suitable soil moisture prediction index, while MNDWI exhibited a weak relationship (R2 = 0.03) with ground data. The strong relationships between soil moisture and tree volume suggest tree volume can be predicted based on available soil moisture content. Any slight undesirable change in soil moisture could lead to severe forest conditions.
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    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.
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    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.