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SUMMARY
Slash and burn or shifting cultivation is a traditional farming system found in many parts of the
humid tropics in general and in Cameroon in particular. Information on farming system in the
moist evergreen forest of southern Cameroon is limited and very sparse. Although the
Cameroon forest action plan did not foresee a significant agricultural pressure on forest land in
southern Cameroon, the shifting cultivation component of the farming system practices may
represent a greater threat to forest conservation than timber exploitation. Understanding the
shifting cultivation practices and the trends and relationships between field expansion, soil
degradation, crop yields and socio-economic factors may provide a basis for determining
research and development strategies and priorities for the improvement of agricultural
production and forest conservation and the achievement of sustainable use of the moist
evergreen forest land. Between 1995 and 1997, a study on this agricultural system practised by
the Bantu population was conducted in the research area of the Tropenbos-Cameroon
Programme (TCP). The general objective was to reduce destructive effects of shifting
cultivation on the forest by proposing to farmers complementary and / or alternative sedentary
practices and by providing information to be utilised for the sustainable forest land use in
southern Cameroon. The methodology followed in the farming system study consisted of site
selection, collection of secondary data through consultation of existing documents, interviews of
key informants and collection of primary data through participatory exploratory survey, case
studies and on farm measurements. The methodology followed in soil degradation study
consisted of site selection, soil description and sampling for laboratory analyses. Trends in
agricultural field expansion were studied by over-laying maps of fields population sample
opened between 1995 and 1997 on the 1984-1985 aerial photo interpretation landscape
ecological map using arc-view software. Results of farming system study showed that a farm in
the evergreen forest of Cameroon is composed of many subsystems interrelated and influenced
by external biophysical and socio-economic parameters. According to 92% of the farmers
interviewed, cropping subsystem remains the first priority activity. In this cropping subsystem,
80% of the farmers considered shifting cultivation involving food crop fields and fallow as their
first priority land use type. Four major crop associations highly linked to the preceding fallow
type were identified in the food crop fields. Today, 76% of food crop fields in the area shift
within fallow of different ages in a rotational system. Only 24% of agricultural fields expand
towards undisturbed forest for cucumber (Cucumeropsis mannii) production and for
establishment of semi-industrial farms by elite. Between 1984 and 1997, the land area under
agricultural use expanded from 31 to 40.3%, for an average annual expansion of 0.71% of the
total land area. The population pressure, the type and objective of crop production, the limited
labour and access to new land have prompted more farmers to abandon the traditional expansive
shifting cultivation to adopt the rotational system. The latter consists of shifting in a total area of
less than 10 hectares, clearing short length fallow. This reduction in fallow length leads to
degradation of topsoil morphology and physico-chemical soil properties. The study of soil
degradation under shifting cultivation showed that the liming effect of ashes from burned
vegetation biomass at the beginning of the cropping period increased significantly (p