Secondary succession in abandoned fields of dry tropical Northern Cameroon

Abstract. This study evaluates the processes of recolonization of abandoned fields by native vegetation under conditions of intensive human activity (fire, intensive grazing, firewood cutting) in a semi-arid tropical region savanna of northern Cameroon. Secondary plant succession was studied in two series of formerly cultivated fields 1–35 yr after the beginning of the fallow period. Floristic changes and the dynamics of woody plant populations were compared between areas with vertisols (clay texture) and sandy soils, as a function of length of fallows. Vegetation changed continuously during the 35 years following field abandonment. However, a very abrupt break occurred between 6 and 10 yr, due to increasingly intense human pressure during this period. Up to that point, ecological models and mechanisms of succession presented in the literature are more or less confirmed by our results. Usually, secondary succession is blocked at a stage of wooded grassland as a result of human activities.