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Other observations

Various species of rare or disappeared crops, especially yam, were reported in the local languages, Adangbe (in Adangbe-speaking areas) and in Akuapem Twi (in Akuapem Twi-speaking areas), during the group discussions and interviewing by questionnaire (table 9.5).

Similarly, a number of wild animals were also mentioned as having disappeared or become rare (table 9.6).

Discussion

The vegetation zone of the study area had been classified as an AntiarisChlorophora association (Taylor 1960). This indicates that it was typified by a closed canopy. Later, Hall and Swaine (1981) classified the vegetation of this same area as southern-marginal forest (SM) and south-east outlier forest (SO) on account of the species they encountered in their extensive studies. The results obtained in the present preliminary studies showed that there are only semblances of the original Antiaris-Chlorophora association as classified by Taylor (1960) since, currently, there are only traces of Chlorophora/Milicia excelsa, which is now found only at Yensiso and is less common than Antiaris toxicaria/africana, which occurs in all the study sites.

Table 9.5 Disappeared or Rare Species of Crops as Reported in Adangbe and Akuapem Twi during Group Discussions

Table 9.6 Disappeared or Rare Species of Wild Animals as Reported in Adangbe and Akuapem Twi during Group Discussions

The differences in classification of the vegetation in the same area by Taylor (1960) and Hall and Swaine (1981) might reflect the extent of deforestation during the 21-year period between the two publications.

The results of our preliminary rapid survey are in total agreement with the current classification by Hall and Swaine (1981). The considerable deforestation suggested by the different classification of the vegetation in the study area is further supported by responses obtained from the group discussions. However, Lawson (1985) also mentioned that some types of forests are characterized by the absence of certain trees - e.g. a "true" rain forest or evergreen forest is characterized by the absence of Celtis and Triplochiton, and that other trees such as Antiaris africana are also characteristic of the drier forest area.

By its nature, the predominant life-form composition in a forest should be tall trees that are above 30 m, with a good blend of trees (t) that are below 30 m. But the results obtained in this study indicated that there were fewer tall tree species, and these were widely spaced apart, and that there were comparatively far more herbaceous species in the study sites (tables 9.2 and 9.4). This scenario or pattern of life-form composition suggests a tendency towards the establishment of a grassland that has few remnant trees.

Possible Causes of the Floristic Change

The floristic changes discussed above are probably due to natural bushfires, and to anthropogenic factors associated with the high population pressure, the quest for fuelwood and poles for construction, and agricultural expansion through the slashbum peasant farming system with its concomitant loss of biological diversity and reduction of fallow periods, in the desperate effort to meet the food requirements of the growing population. In some of the localities, such is the level of the demand for food that the land is farmed continuously, resulting in a decline in soil quality and an increase in soil erosion.

The transformation of a once forested land into a grassland is followed or accompanied by invasion by opportunistic herbaceous species such as: Chromolaena odorata, Canna indica, Coccinia grandis, Commelina capitula, Acanthospermum hispidum, Ageratum conyzoides, Bidens pilosa, Lactuca taraxacifolia, Tridax procumbens, Digitaria diagonalis, Eleusine indica, Paspalum orbiculare and Sporobolus pyramidalis.

The Hazards and Potential Benefits of Chromolaena Odorata

It is hypothesized here that the presence of Chromolaena odorata as the predominant species in all the study sites has been an opportunistic event associated with the deforestation and the attendant break in canopy of the original closed forest as classified by Taylor (1960). C. odorata is still behaving exactly this way and can be found in gaps created artificially or otherwise in the forest.

C. odorata is a primary noxious weed that is next to impossible to eradicate. Its growth is incredibly luxurious, and it completely takes over any land that it invades, excluding all other species. During the dry season, it dries up only to regenerate at the onset of the rains. Its dry stems are believed to be highly flammable and a potential fuel source for accidental/natural bushfires. Furthermore, once this species arrives at any locality, its incredible morphology and high competitiveness enables it to out-compete, outgrow and thus ex clude all other species from its immediate milieu. It thus constitutes a serious problem.

However, local farmers claim that C. odorata, popularly called akyeampong, improves soil fertility if it is the predominant species growing on fallow land. A PLEC soil scientist and others have initiated steps towards the verification of this claim on the basis of quantitative data, so that the results, if positive, might form a basis for the optimum management of this plant for farming purposes.

Conclusion

On the basis of this study, it can be said that the vegetation of the forest-savanna zone is undergoing degradation, including the loss of floristic diversity, which might be countered by encouraging longer fallows, preservation of hillsides and endangered natural habitats, and other anti-deforestation measures.

References

Hall, J.B. and Swaine, M.D. 1981. Geo. Bot. 1. Distribution and Ecology of Vascular

Plants in a Tropical Rainforest. Forest Vegetation in Ghana. The Hague: W. Junk.

Lawson, G.W. 1985. Plant Life in West Africa, pp. 16-33, 34-50. Accra: Ghana Universities Press.

Taylor, C.J. 1960. Synecology and Silviculture in Ghana. Edinburgh: Thomas Nelson.

10: Population growth and urban demand

Population growth
Urban demand
Conclusion
References

John S. Nabila

The growth of the population and the attendant increased pressure on the land and geographical redistribution of people, which appeared to be a fundamental factor in the environmental change in the southern sector of the forest-savanna transition zone, are examined in this paper using data from the PLEC 1993 field studies and from documentary sources. This factor can be discussed from the following viewpoints:

• the predominantly rural population of the zone itself; and
• the population of the urban areas of which this zone constitutes a hinterland and source of supply of primary products.

Each of these exerts its own demands on the agrobiophysical resources.

Population growth

The population of the surveyed settlements had a substantial migrant component, and showed significant changes since 1960 (table 10.1). The phenomenal population growth in Amanase, Yensiso and Kokormu, in contrast to the general decline in Osonson, Whanabenya and Adenya, is indicative of population redistribution and adjustment in response to differential environmental conditions, including different degrees of environmental degradation as perceived by the people.

Table 10.1 Population Growth in the Surveyed Settlements

Source: Based on 1960 and 1984 population census reports.

Table 10.2 Ethnic Composition of the Sample of Farmers Interviewed at the Study Sites in October 1993 (shown by percentage)

Source: PLEC 1993 field study.

Amanase, Whanabenya, Sekesua and Osonson were founded in the early parts of this century by migrant cocoa farmers from Akuapem district in the case of Amanase, from the Siade/Shai area in the case of Whanabenya, and from Krobo country in the case of Sekesua and Osonson. Yensiso and Adenya probably existed as small Akuapem hunting and oil-palm growing hamlets before the founding of Amanase, Whanabenya, Sekesua and Osonson, but expanded after the introduction of cocoa there during the 1900s. Kokormu probably was a later creation by the Ayigbe and Ewe migrants who settled there, perhaps around 1950, for the purpose of food crop farming, which is now the leading economic activity of the forest-savanna zone inhabitants, including the migrants, who comprised mostly:

• Twi-speaking Akuapem in the Yensiso and Amanase areas;
• Adangbe-speaking Krobo in the Sekesua area;
• Adangbe-speaking Siade in the Amanase area; and
• Ayigbe and Ewe in the Yensiso area.

Others were the relatively few Kyerepong-speaking Akuapem concentrated in the Yensiso and Amanase areas, and other Akan-speaking people and non-Ghanaians found in the Yensiso area. The detailed distribution is shown in table 10.2.

Our estimate of the average population density per square kilometre for the whole forest-savanna zone is 161 or more in 1993. Table 10.3 shows the 1984 densities for the local council districts where the study areas were located. They ranged from 139 to 178 persons per square kilometre, compared to the national average of about 51. Since these figures are for 1984, they are likely to differ somewhat from the present situation. For instance, the Manya Krobo local council population stood at 140/km² in 1970, compared to 108 in 1984, a decrease which, like decreases in other rural areas, most probably represents outmigration in response to environmental deterioration. However, on the whole, the population densities within the forest-savanna zone were expected to be on the increase in accordance with the general national trend.

Table 10.3 1984 Population Densities for Local Council Districts Where the Study Areas Were Located

Source: Ghana Statistical Services 1989.

The population factors analysed above have varying degrees of implication for the status of the environment. The increase in the absolute numbers of people is a major source of stress on the environment through farming and extractive activities. On the basis of the 1970-84 growth rates, the populations of Kokormu, Amanase and some other villages are likely to more than double by the year 2000, resulting in increased pressure on the already stressed land and other resources (table 10.1). The depopulation which some of the areas are likely to continue experiencing might not significantly alter the environmental degradation because of the severity of the damage already done and the lack of the corrective wherewithal in the affected rural areas.

As the quality of the environment declines, so do the yields, earning and living standards. In particular, the continuous cropping of the increasingly fragmented fields leads to land impoverishment and consequent low output. It is not surprising therefore that 25 per cent of the households could no longer adequately feed themselves with the produce from their farms. Significantly, the figure for Amanase, which showed the highest population growth rate among all the villages surveyed, was 45 per cent. These findings about the environmental effects of the population changes suggest the need for population control in conjunction with other mitigating measures.

Urban Demand

The pressure exerted by population on the biophysical environment is transmitted in various ways, especially through the demand for products derived directly or indirectly from the environment. The demand originates from rural and urban areas within a country itself, and from other areas outside the country. We carried out surveys in rural markets at Adawso (near Yensiso), Sekesua and Amanase, in a preliminary attempt to determine the character of this demand on our study areas, particularly in terms of what is taken out and their destinations. The results are summarized in tables 10.4 and 10.5 and in figure 10.1.

Table 10.4 Types of Commodities Destined out of Adawso, Sekesua and Amanase Markets (percentages)

Source: Based on market surveys by sample in October 1993.

Table 10.5 Destinations of Commodities Purchased by Middlemen from Adawso, Sekesua and Amanase (percentages)

Source: Based on market surveys by sample in October 1993.

Figure 10.1 Destinations of Commodities from Adawso, Sekesua and Amanase

On the whole, food items, most especially unprocessed primary agricultural ones, led by cassava, comprised nearly 91 per cent of the commodities destined out of the three markets, which confirms the significance of farming as a factor in the environmental change. About 9 per cent of the commodities that were destined out consisted of other items, including firewood and charcoal, whose production contributes significantly towards the depletion of the forests.

On the average, 91 per cent of the commodities were destined for urban settlements,! most especially Accra-Tema, Ghana's largest settlement, a finding which is in general conformity with a previous observation with respect to the Sekesua market (Gyasi 1976). The remaining 9 per cent were destined for rural settlements which, like the urban destinations, were located within or near the forest-savanna zone (fig. 10.1). It is evident then that the demands of the urban centres are a significant source of stress on the forest-savanna environment. In the past, much of the production pressure placed on this zone originated from outside Ghana. It took the form of external demand for minerals and primary agricultural and forest products, notably palm oil, cocoa and timber.

Conclusion

There is little question that the main driving force behind the environmental change in the southern forest zone is population pressure. Rapid increases in the absolute numbers of people, their uneven spatial distribution, and the demands from urban centres within the country and from outside the country exert varying degradational effects on the biophysical resources of the zone. The threat to the environment is aggravated by unfavourable climatic trends. This underscores the need for population control, floral and faunal conservation programmes and other environmental rehabilitation measures, particularly through education.

Note

1. An urban settlement is defined as a settlement having a total population of 5,000 or more, whilst those having less than 5,000 are considered rural (Central Bureau of Statistics 1984; Statistical Services 1989).

References

Central Bureau of Statistics. 1984.1984 Population Census of Ghana: Preliminary Report. Accra.

Gyasi, E.A. 1976. Population pressure and changes in traditional agriculture: case study of farming in Sekesua-Agbelitsom, Ghana. Bulletin of the Ghana Geographical Association 18: 68-87.

Statistical Services. 1989.1984 Population Census of Ghana, Special Reports on Localities by Local Authorities.. Accra.

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