Odzala-Kokoua National Park- Gorilla Trekking in Congo

Odzala National Park is known as “one of the most important strongholds for forest elephant and western gorilla conservation remaining in Central Africa” In the Cuvette-Ouest Region of the Republic of the Congo. Founded in 1935, the park now covers 13,600 km2. The park is located in the north-west of the Republic of Congo (Congo-Brazzaville).

Odzala-Kokoua National Park in Congo’s remote north-west is one of Africa’s oldest national parks, having been proclaimed by the French administration in 1935.  It has pristine rainforest and is an integral part of both the Congo Basin and the TRIDOM Trans frontier Park overlapping Gabon, Congo and Central African Republic.

Covered in forests, rivers, marshes and swamps, the Park receives some 1 500 mm of rain annually, mainly during the two wet seasons. Permanent rivers are a primary feature, with the Lekoli and Kokoua rivers flowing into the Park’s major channel, the Mambili. In some places, the Mambili is up to 100 metres wide between densely forested banks; it then flows into the great Congo Basin.

Bais, or salines, are major features of this rainforest. These swampy, grassy areas are dotted across the rainforest and offer a rare chance to catch a glimpse beyond the ‘green curtain’ into the lives of the forest dwellers. Various mammal species come to the bais on a regular basis in order to access various elements, from water to minerals and salts to sedges and water-loving grasses to water.

As of 1996, the entire area of the reserve is found within the catchment area of the Mambili River, which drains the area towards the south. The region is quite varied due to the juxtaposition of several habitat types, including savanna, forest and rivers. The site is astride the savanna-forest boundary of North-Central Congo, allowing for a high biodiversity of flora and fauna, with species from forest, savanna and riverine forest. The area is densely forested in the northwest; towards the south and east the forest becomes more open with an understorey of Marantaceae carpeting the ground. In the south of the region an extensive forest-savanna mosaic is found, including gallery forests and dry and swamp savanna.

Two broad forest types are present: forests of hydromorphic soils, and forests of terra firma. The forests of terra firma are the most extensive, and may be further subdivided into closed canopy forests and open forests. The forests of terra firma are generally quite heterogeneous in terms of species, although patches of Lophira alata-dominated forest exist.

In Odzala, both forest types of terra firma are classed as Marantaceae forest: that is, the understorey is an often impenetrable mass of lianescent or erect giant herbs in the family Marantaceae. This forms a thick carpet, up to 3-4m deep, giving the impression of a giant ‘lawn’ through which tree seedlings must grow to reach the light.

In the open Marantaceae forests, the middle-sized trees are much less common than in a closed-canopy forest, sometimes giving one the impression of being an ant in a lawn, with trees so far apart that they are like a London park!.

Data from transects in Odzala show that both tree density and basal area of Marantaceae forest is much lower per hectare than “classic” tropical humid forests of Central Africa. Marantaceae forest is thought to be a stage in the succession of the forest recolonization of the savanna. Several other forest types are recognizable at Odzala as stages in this succession.

The marsh forests are quite extensive, especially along the floodplain of the Mambili. They are generally relatively short, dense forests, often dominated by Mitragyna ciliata, and do not have the thick carpet of Marantaceae found on dry land. Beside the Mambili, patches of monodominant or bi-dominant forest occur, of Gilbertiodendron dewevreii and/or Guibourtia demeusei. Smaller patches of low diversity forest occur on marshy soils here and there, the most frequent of which are Raphia swamp, Xylopia forest, Phoenix reclinata patches and Pandanus swamp.

The savannas have a low biodiversity, both in terms of plants and mammals. The mammal species that are truly savannicole or species of edge habitat include Grimms’ duiker, bushbuck, and spotted hyaena, although the latter seems to have found a niche in the forest near marshy clearings in Odzala. Forest buffalo are found in large troops in the savanna, whereas they are normally found in small groups of up to 12 in forest. The savannas are being recolonized by forest, both from the existing forest edge and from small thickets originating on termite mounds within the savanna itself. Until the late 1990s, lions lived in the park and the savannahs to the south, but now seem to have gone – not only from here but from the whole of the Bateke Plateau, where they were once not uncommon.

Within the forest bloc, swampy forest clearings provide abundant digestible forage for herbivores such as gorillas, buffalo, sitatunga and giant forest hog. In addition, some of these clearings have salt-rich soils, which attracts elephants as well as other mammals. These clearings are probably maintained by the action of the larger herbivores, and provide the rare opportunity of observing forest species which are normally extremely difficult to see.

Density estimates of apes and elephants have been calculated from the park. Comparison of these results and of data obtained elsewhere using the same methodology shows that Odzala has high densities of both of these species; the open canopy Marantaceae forests have a particularly high gorilla density, and closed canopy Marantaceae forests have a high chimp density.

It is probable that the Marantaceae itself is an important keystone resource in Odzala, as has already been proposed for Lopé National Park in Gabon. The riverine forests are used by all eight monkey species which occur in the park, and four of these are never or rarely seen in forests of terra firma (De Brazza’s monkey, Angolan talapoin, Mantled guereza, Tana River mangabey). The rivers and marsh forests are also important for other species such as hippo, chevrotain, sitatunga, Nile monitor, dwarf forest crocodile and Slender-snouted crocodile, and the marshy clearings mentioned above are also very important for the large mammals of the region.

The major problems in terms of conservation for the region are elephant poaching for ivory and hunting of other animals for the commercial bush meat trade. Elephant hunting was greatly reduced for a while with the implantation of a conservation project (ECOFAC), due to their antipoaching activities. However due to the rising price of ivory poaching has risen again. In 2011 the African Parks Network took over management of the site.