A Spatio-Temporal Based Estimation of Vegetation Changes in the Tarkwa Mining Area of Ghana

摘要

The Tarkwa Mining Area (TMA) falls in the rainfall belt of Ghana with evergreen Equatorial forest vegetation. TMA has witnessed clearance of large tracts of vegetation to make room for mining and settlements. Destruction of vegetation has exacerbated since surface mining was introduced in the area in the 1980s. However, the actual extent of vegetation change since 1980 to date has not been assessed and quantified. This study uses Remote Sensing (RS) and Geographic Information Systems (GIS) techniques to estimate the changes in vegetation in the area. Temporal satellite images for four different years and 250 ground reference points were classified using maximum likelihood algorithm. The impact of mining on vegetation composition was also estimated using distant gradient. Phytosociological analysis was also carried out to determine the species density, dominance index and diversity index. The results revealed five dominant land use/cover types. Vegetated areas in the TMA lost 932.92 km2 whereas settlements and mining areas gained 932.93 km2 of land. A phytosociological analysis of the TMA revealed that the number of herbaceous species colonizing the mined areas was much higher than the number colonizing the unmined areas. The study concluded that the rate of changes in the various land-use/cover types in the TMA is alarming and if the current trend of development continues, there could be an imbalance in the ecosystem of the TMA.