Assessment of deforestation,biodiversity loss and the associated factors: case study of Ijesa-Ekiti region of Southwestern Nigeria |
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Authors: | Nathaniel Olugbade Adeoye Bola Ayeni |
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Institution: | (1) Department of Geography, Obafemi Awolowo University, Ile-Ife, Nigeria;(2) Department of Geography, University of Ibadan, Ibadan, Nigeria |
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Abstract: | Deforestation is driven by a variety of factors, and has resulted in land use changes that threaten biodiversity, water and
energy resources. However, lack of reliable data and survey information in Nigeria has made the estimation of the effect of
deforestation difficult to establish. Consequently, the extent and rate of deforestation are less well known. The study therefore,
examined and analyzed the spatial and temporal patterns of deforestation over the period of 25 years (1978–2003); measured
the rates, trends and explained the factors that determined deforestation in Ijesa-Ekiti region of southwestern Nigeria. The
major sources of data for the study were satellites images. These were Landsat MSS 1978, with spatial resolution of 80 m,
SPOT XS 1986, SPOT XS 1994, with 20 m spatial resolution and NigeriaSat_1 2003, with 32 m spatial resolution. To make them
comparable, they were georeferenced to the same coordinates system, filtered, resampled and enhanced for visualization in
a GIS environment. Furthermore, Ilesa, Ijebu-Ijesa, Efon-Alaaye, Iloko-Ijesa, Erin-Oke and Erin-Ijesa were identified and
selected for ground truthing to validate the tonal values recorded in the images with the features on the ground. The result
of ground truthing was combined with visual image interpretation as training sites for supervised classification. Focus Group
Discussions were held with people who had lived in the area for over 20 years as a means of eliciting factors of deforestation
and the effects on forest biodiversity. The results indicated forest loss of 53,469.23 ha over the period of 25 years at an
annual deforestation rate of 7.21, 2.47, and 5.40% per year for 1978–1986, 1986–1994 and 1994–2003, respectively. FGDs with
various categories of people in the bigger towns confirmed deforestation in the area and were due to illegal lumbering, intensive
agricultural practices and growth of settlements resulted from increase in human population. FGDs also revealed extinction
of many forest species in their communities. In conclusion, the study advanced our understanding on techniques of analyzing
deforestation using geo-spatial technology. It also generated a synthesis of information on the rates of deforestation and
its driving forces, which are a complex mix of anthropogenic factors, the chief of which has been the conversion of forest
resources to agricultural land use. |
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