View of Mpassa project area, Gabon. rel=
View of Mpassa project area, Gabon.
© WWF / Martin HARVEY

Unexpected features of the Congo River Basin

Dry, parched, and usually devoid of the fast-paced turnover of ecological processes in tropical areas, savannas are not a feature one would expect in the Congo River Basin. However, on the fringes of the rainforests, they are an increasingly normal pattern.
Forests at the northern and southern end of the Congo Basin rainforest block have often been replaced by grassland, which often occurs in a mosaic with patches of original and secondary forests. The boundary of forest savanna areas is constantly changing, depending on the impacts of fire and the interventions of humans. 

Several kinds of mosaic are found, including:
  • Savanna with a few forest blocks
  • Savanna with gallery forest (tree formations alongside river banks)
  • Forest with enclosed savanna

The Southern Congolian forest-savanna mosaic ecoregion

In the southern part of the Congo River Basin, moist forest gives way to great stretches of savanna and grassland. This is a result of the region's large climatic fluctuations over the last 10 million years and of human activities - especially cultivation and burning. Wildlife here includes bongos, bushbucks and buffalo.

The ecoregion includes the southern central portion of the Democratic Republic of the Congo and the northwestern corner of Angola. Small, lush forests called gallery forests grow along the waterways, while elsewhere the vegetation consists of a mix of lowland rainforest, dry forest and secondary grassland.

Among the many trees that grow in the region are false chew sticks(Garcinia polyantha), Senegal date palms (Phoenix reclinata), East African mahoganies (Khaya nyasica) and African breadfruit (Treculia africana)

Other trees and shrubs in the region include acacias (Acacia species), wild custard apple trees (Annona senegalensis) and the pink jacaranda(Stereospermum kunthianum) - a small tree with a rounded umbrella-like crown and pink blossoms. 

How elephants share the local ecology

Elephants spend their days eating leaves from small trees, leaving denuded and toppled trees in their wake. This activity helps create grasslands in the region because large concentrations of toppled trees keep saplings from growing, and they fuel fires that burn back any trees that manage to sprout. 

Other mammals of the savanna

Bongos (Tragelaphus eurycerus), defassa waterbucks (Ellipsiprymnus defassa), and roan antelopes (Hippotragus equinus) are all present in small numbers after years of heavy hunting. 

Other large mammals in the region include southern reedbucks (Redunca arundinum), oribi antelopes (Ourebia ourebi), buffalo, hippopotamuses (Hippopotamus amphibius), and blue (Cephalophusmonticola), yellow-backed (Cephalophus sylvicultor) and grey duikers (Sylvicapra grimmia).

Birds and amphibians

Brown and green Meyer’s parrots (Poicephalu meyeri) live in these savanna woodlands as well. The brown kasai reed frog (Hyperolius obscurus) and the spotted tshimbulu reed frog (Hyperolius polli) also call this ecoregion their home. 

Today, large-scale clearings for agriculture, urban development, logging and mining create conditions in which many trees can no longer regenerate. Poaching, soil erosion and water pollution are also threats, while conflicts between elephants and subsistence farmers threaten elephant populations.