Land use and cover sequences

Land use succession as identified in the present study area and as may be used for the biophysical, socio-economic and technological analysis of land use change in the forest areas of Ghana is described in figure 14.2.

A sequence involving cocoa cultivation as an export cash crop, food cropping as both commercial and subsistence activities, oil-palm and other tree crops as cash crops is shown (Akin 1958; Dickson 1969; Dickson and Benneh 1988; Field 1943; Gyasi et al. 1994; Hill 1963; Howard 1978). The technological and socio-economic conditions associated with each of these land uses as well as the factors influencing them provide the basis of analysis and characterisation of the various stages of the development of the land use and cover sequences.

Figure 14.1 General Land Use and Cover Change Model in the Savannas of Northern Ghana (Source: Rose-Innes 1964)

Figure 14.2 Land Use and Cover Sequences in the Yensiso-Sekesua-Amanase Study Areas

(r) Decisions influenced by internal factors of population, urbanisation, transportation and policy

Þ Mainly external factors of international production demand and prices

Cocoa Cultivation

Cocoa cultivation on virgin forest land involves the slashing of the undergrowth of shrubs, saplings of emergent tree species and of the stems of climbers that may reach the tree canopy. Selective removal of trees is carried out by felling or by burning and the debarking of the trees at the base above the ground to open up the canopy to allow enough light in for growth of the cocoa trees and the broad-leaved food crops, for example cocoyam and plantain. A modified environment and habitat are created. In the study areas forest with varying degrees of canopy degradation or fallow regrowth occupied between 38 per cent and 56 per cent of the study sites. Closed canopy occupied 0.2 per cent. At maturity, the cocoa plants provide the lower canopy of the modified land cover and habitat.

The Abandoned Cocoa Land and Land Use Choices

The bearing life span of the cocoa plant is about 30-40 years, depending upon the soils. The trees may die of disease, fire or age. The land use is then abandoned, although the harvesting of fruits and food crops such as cocoyam, yam and plantain may continue. The farmer's decision as to the use to which the abandoned cocoa land is put depends upon several factors, including principally the relative prices and profitability of cocoa, other tree crops such as oilpalm, coffee, citrus and food crops of cocoyam, plantain, maize, cassava and vegetables. The relative prices of these crops are influenced by population growth, urbanisation and the demand for food, industrialisation and the demand for agricultural raw materials, the external production conditions and markets, such as for cocoa and oil-palm, and finally upon government policies. External factors for Ghana have included increasing competition from other countries which also produce these commodities.

Within these choices, specific cropping patterns have been adopted to offset the changing conditions in the biophysical environment: for example, the increasing preference for maize and cassava as compared to plantain and cocoyam, and the preference for varieties of the same crops, such as cassava, that may be more suitable to the changing environmental conditions (Gyasi et al. 1994).

The sequence of uses and cover is, therefore' not unidirectional, and depends upon important factors. Within any choice the technology adopted is important as regards the end state of the environment and the productivity of the land. In the study area, the change from tree crops to food crop cultivation involves change from simple slash and burn with machetes and fire and no tilling to the increasing use of more disruptive methods, e.g. stumping and hoeing.

Cutting of New Forest

The normal reaction of the farmer to an old or diseased, non-bearing cocoa farm is to search for new forest land locally or outside the locality. This was possible in the past up to the 1960s, when migrant cocoa farming was an important phenomenon in the forest areas of Ghana (Arhin 1985; Hill 1963). This land use choice is no longer available, with only 0.48 per cent of Ghana's high forest area of 86 million ha remaining outside the reserve system (Ghana 1987). Estimates based on aerial photographs of land under closed canopy forest in the study sites are insignificant in both Yensiso and Amanase, where such land accounts for less than 1 per cent in both areas (Gyasi et al. 1994; see also chap. 7, this volume).

Secondary Regrowth Forest

Under conditions of abundant forest lands, the abandoned cocoa farm would be left to develop into a secondary regrowth forest. The development of regrowth vegetation in the forest has been described by Ahn (1958). The use of such land includes the gathering of non-timber forest products (NTFP), such as canes, fruits, leaves and animals. Commercial timber is also cut. The regrowth forest may eventually be cultivated to cocoa. This choice is hardly available now because the cocoa land can hardly be left for a sufficiently long period for forest conditions to develop, a period generally above 25 years. This used to be the felling cycle recommended by the Forestry Department in the reserved forests.

Replanted Abandoned Lands

Abandoned lands may be planted in cocoa, oil-palm, citrus or other tree crops. Cocoa farming in the study sites (and indeed in southern Ghana in general) was devastated by the swollen shoot disease beginning in the late 1930s (Dale 1962). A project to rehabilitate and replant old diseased cocoa farms by the Ministry of Agriculture was started in 1948 in parts of the country that include the present study areas. The results of the various phases of the project indicate that replanting is yet to be widely developed, though it is considered important in a situation where no more forest land is available.

It has been observed that only 12 per cent of those operating the generally old cocoa farms had attempted to rehabilitate them (Gyasi et al. 1994). The problems of replanting may partly arise from the loss of income to the farmer while rehabilitation and replanting take place. The modified environmental conditions resulting from the first cycle of cultivation may also pose problems, for example of fire. Replanting may be done under existing modified forest cover conditions of the old farm or without a forest cover, in which case broadleaved food crops are used to protect the young cocoa plants. Oil-palm cultivation also requires complete conversion of the forest cover. Experiments are being conducted at the Cocoa Research Institute at Tafo to find solutions to the problems of replanting.