Coastal forest and Miombo woodland history of the Vilankulo region, Mozambique

Abstract

The present day distribution of Miombo savanna-woodland in Mozambique has been attributed to an expansion due to the clearing of original coastal forests through agriculture and use of fire. Here, we test this hypothesis using palaeoecological data from Lake Nhauhache, situated in the Vilankulo region. Our analysis shows that Brachystegia, one of the main constituents of the Miombo, has varied over time, and its variability seems to be driven by hydrological changes related to climatic variability rather than by land-use changes. The analyses show that Brachystegia was most common during ad 200–700 when a marshy forest/shrub community was dominant. After ad 700, this community changes to a dominance of Syzygium and Fagara linked to gradually rising water levels. Brachystegia remains in low abundance and fluctuating over time. From ad 1000, a general decline in trees/shrubs in favour of grasses concurs with an increase in grass pollen (possibly cereal) and charcoal, most probably as a result of farming activities. The decline in tree taxa was probably exacerbated by periodic droughts after c.ad 1200 as indicated by the diatom assemblage. In the period ad 1700 to late 1800, arboreal pollen is well represented, and this is concurrent with the diatom record suggesting high lake levels.