二次林におけるプランテインの持続的生産--カメルーン東南部の熱帯雨林帯における焼畑農耕システム (特集 森からみたアジア・アフリカ)

Abstract

Farmers in the tropical rain forest of Africa are mainly involved in shifting cultivation activities that are criticized as a principal cause of deforestation. However, such criticisms are narrated on the basis of forest protection, rather than understanding the ecological role of what they are actually doing. This study aims to clarify the shifting cultivation system of the Bangandou farmers who live in the tropical rain forest of southeastern Cameroon with special reference to their plantain cultivation. The Bangandou grow several crops for subsistence and cacao as a cash crop. They also depend on foraging, hunting and fishing to get animal protein and to enrich their diet. Their agricultural land use is characterized by three kinds of fields: fields of starch crops, including plantain, cassava, maize and cocoyam, opened in secondary forest near villages; cacao fields in virgin forest close to rivers; and groundnut-maize fields on sandy riverside land. The main staple food of the Bangandou is plantain, which they are able to harvest throughout the year by staggering the time of planting and using several varieties with different growth periods. This plantain-based system is maintained by the periodical use of the secondary forest dominated by the quick-growing Musanga cecropioides R. Br., in which weeding is practiced for about one year after clearing and then abandoned thereafter. Plantain keeps growing and fruiting even in such bush-like "fallow fields, " and people can therefore continue harvesting plantains from several fields opened in different years. The Bangandou have thus managed to achieve the stable production of plantain and the sustainable use of the secondary forest in such a way that the fallow starts during the harvest period of plantain, which assists the quick regeneration of the forest.