|Environment, Biodiversity and Agricultural Change in West Africa (UNU, 1997, 141 pages)|
|Pilot study of production pressure and environmental change in the forest-savanna zone of southern Ghana|
|7: Land use and cover patterns|
The photo interpretation identified the following broad land use and cover categories:
Table 7.1 contains the aerial photographic estimates of these land use and cover categories for Yensiso, which is characterised by the Akuapem-Ayigbe-Ewe mosaic landholding and usage pattern (fig. 6.1, p. 44), and for Amanase, which is characterised by both the Akuapem Ayigbe Ewe mosaic land use pattern and by the Krobo-Shai/Siade linear huza pattern (fig. 6.2, p. 45). Broken canopy forests and mature fallows, commonly containing oil-palms, fruit-trees (particularly mango and orange) and staple crops (cassava, plantain and cocoyam) with occasional cocoa farms, covered some 39 per cent of the interpreted Yensiso area, compared to about 57 per cent for Amanase. Amanase's larger proportion apparently reflects the presence of more cocoa farms, which are associated with broken canopy forests. This conjecture is supported by our ground traverse observations, and by the fact that the Amanase area was considered important enough as a cocoa producing area for inclusion in an extensive cocoa rehabilitation project in the 1970s. Current arable cultivation and short fallows occupied 61 per cent of the Yensiso area, compared to Amanase's approximately 43 per cent, which are indicative of greater pressure on land in the Yensiso area. A significant source of the pressure in Yensiso was the 406 ha cleared for the state-owned oil-palm plantation located at Kwamoso. The proportion of land under remnant forest with closed canopy was insignificant in both Yensiso and Amanase.
Table 7.1 1974 Aerial Photographic Estimates of Land Use and Cover Areas for Yensiso and Amanasea
|Use and cover||Yensiso||Amanase|
|Broken canopy forests and old mature fallows||1,683||38.6||2,490||56.6|
|Current arable cultivation and short fallows||2,653b||60.9||1,899||43.2|
|Remnant forest with closed canopy||20||0.5||8||0.2|
Source: 1974 aerial photographs supplied by the Survey Department,
a. Sekesua is omitted because the land use and cover types identified in the aerial photographs of the two other areas (Yensiso and Amanase) could not be clearly distinguished in the Sekesua aerial photographs.
b. Includes 406.1 ha (9.3%) for the state-owned oil-palm plantation of Kwamoso.
The Sekesua area, settled by migrant Krobo people on the basis of the linear huza agricultural land use system, showed near complete removal of the forest cover for cropping. Huza strip orientations, unlike the cultivated plots, were identified on the aerial photographs (fig. 6.3, p. 46). The Sekesua aerial photographs indicated a restriction of the limited dense bush or forest to narrow valleys, steep slopes and other localities of difficult access. The topography here is rather broken.
The ground traverse surveys show the disappearance of forest cover and the extensive conversion to agricultural land use. Two major land use and cover types, namely cropped lands and fallows, were observed. Others of a lesser coverage comprised settlements and roads. The traverse survey results are shown in table 7.2. An average of 54.4 per cent of the land in the three study sites was in active crop cultivation. The percentage distributions of the actively farmed lands ranged from 41.7 per cent in Sekesua to as high as 63.2 per cent in Amanase. The farms were generally intercropped with cassava and maize as the principal crops. Relict cocoa farms occurred under broken canopy tree cover. Several fields in Kokormu, Gyeabor and Yensiso and other localities in the Yensiso area were reported to have been cropped almost continuously since about 1950, when Ayigbe and Ewe migrants reportedly started renting land from the Akuapem owners for food crops. The continuous cropping had led to noticeable soil impoverishment and decreased crop yields in spite of the use of artificial chemical fertilizer and improved crop varieties. Home gardens fertilized with household refuse constituted a fairly significant proportion of the actively cultivated land, particularly within 500 m of the villages. The proportion of the total area covered by fallows was 34.3 per cent in Yensiso, 34.8 per cent in Amanase, and 41.7 per cent in Sekesua, with the average fallow period ranging from one to two years. The fallows were generally invaded by the weed Chromolaena odorata, popularly called akyeampong. We estimate the area in fallow, farms and other uses to cover over 90 per cent of the total area, which shows a remarkable correspondence with a 1990 estimate for the Mampong Valley Social Laboratory area, including Yensiso and the adjoining study sites (Gyasi et al. 1990).
Table 7.2 Distribution of Major Land Use/Cover along Traverses in Yensiso, Amanase and Sekesua in Metres and Percentages
|Land use/cover||Yensiso||Amanase||Sekesua||Average of the percentages|
Source: October 1993 ground traverse survey along selected paths/roads from the study sites.
Table 7.3 Percentage Distribution of Land Use/Cover in Relation to Walking Distance along Traverse Paths from the Settlements
|Yensi- so||Ama- nase||Seke- sue||Yensi- so||Ama- nase||Seke- sue||Yensi- so||Ama- nase||Seke- sue||Yensi- so||Ama- nase||Seke- |
Source: PLEC 1993 ground traverse survey.
In line with findings of previous studies (Chisholm 1962; Gyasi 1979; Gyasi et al. 1990), there appeared to be some relationship between land use/cover and distance from the settlements (table 7.3). The active farms tended to concentrate within the first 1,000 m (1 km) from the settlements, especially in Amanase, and the proportions of fallow and other uses showed rather irregular variation along the traverses.
Evidence of the original forest environment were small random pockets of remnant forest and more extensive areas of broken canopy forest. Wide areas at Yensiso and Amanase showed complete change from forest through perennial cocoa crop to seasonal arable crops. The change appeared even more dramatic in Sekesua, where there were only small pockets of tree cover limited to the areas of difficult accessibility. It is evident then that farming and other land uses have displaced very nearly all the original natural forest, and threaten to eliminate the rest.