Data from: Paleo-trajectories of forest savannization in the southern Congo

Tropical savanna and forest are thought to represent alternative stable
states in ecosystem structure in some climates. The implication is that
biomes are maintained by positive feedbacks, e.g., with fire, and that
historical distributions could play a role in determining modern ones. In
this context, climate alone does not govern transitions between biomes,
and understanding the causes and pathways of such transitions becomes
crucial. Here, we use a multi-proxy analysis of a 2000-year core to
evaluate modes of transition in vegetation structure and fire regimes. We
demonstrate a first transition c.1540 BP, when a cyclic fire regime
entered a forested landscape, eventually resulting, by c.1060 BP, in a
transition to a more open savanna-like or mosaicked structure. This
pattern may parallel currently accelerating fire regimes in tropical
forests suggesting that fires can savannize forests, but perhaps more
slowly than feared. Finally, c.540 BP, a drought combined with
anthropogenic influences resulted in a conclusive transition to savanna,
probably resembling the modern landscape in the region. We show here that
fire interacted with drought to transition forest to savanna, suggesting
that disturbance by fire can be a major driver of biome change.