The nexus of population change, agricultural expansion, landscape fragmentation in the Volta gorge area, Ghana

Abstract

The research combines a spatio-temporal analysis of observed changes in a time-series landcover mapping for the years 1975, 1990, 2000, 2003, and 2007 with socio-economic variables such as data on agricultural productivity and population parameters to explain the phenomenon of change in the Volta gorge area.  It reveals the pattern of change in landscape and how that corresponds to human factors such as increased population, demand for food and consequent expansion in agricultural activity in the modification of Landscape. The period under consideration (1970-2007) witnessed an increase in population size and household number by about 48% and 42% respectively, though household sizes did not witness a comparable change. The population size correlated positively and very strongly with the crop yield (r²=0.85), cropped area (r²=0.53), agricultural cover class (r²=0.74) but negatively with Closed forest (r²=0.91) indicative of the high level of conversion of forest resources. Fragmentation analysis using the following indicators; Number of patches (NP), Largest Patch Index (LPI), Patch Density (PD) and Mean Patch Size (MPS) was computed with the FRAGSTATS® software. These metrics generally reveal the varied change within and among classes and also from year to year. For example increase in conversion of forest into cropland corresponds to the increase in the number of patches for the initial years and a decrease for the latter years.

Keywords: Population, Landcover, fragmentation, Agriculture, Volta gorge