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The Savannah Biome
Odzala-Kokoua National Park encompasses over 42,000 hectares of savannah. These remnants of the ancient Sangha Interval savannahs once separated the tropical forests of Lower Guinea and the Congo Basin. This unique landscape preserves the ecological heritage of a bygone era when vast grasslands divided two of the world's major tropical forest regions."

Understanding the Savannah Biome: More Than Just Grasslands

The word "savannah" is often misunderstood or used incorrectly. In Anglophone parts of Africa, many people prefer the term "grassland." However, these terms are not the same. "Grassland" refers to a type of vegetation formation that is primarily composed of grasses, with few or no trees or shrubs.

In contrast, a "savannah" represents a biome, which means a set of different subtropical or tropical environments resulting from the same combination of climatic and ecological factors (e.g., water availability, light intensity, nutrient levels, altitude).

Savannahs are dominated by grasses, with or without woody strata. These open plains have unique ecological dynamics and serve as a crucial source of nutrients for the soil, unlike the lusher grasslands found in East Africa.

The Distinctive Savannahs of Odzala-Kokoua National Park

The southern part of Odzala-Kokoua National Park, which is the section accessible to visitors, encompasses approximately 42,000 hectares of savannahs. These landscapes are remnants of the ancient Sangha Interval corridor, which historically separated the tropical forests of Lower Guinea to the west from the Congo Basin to the east. As the climate became more humid around 1,500 to 2,000 years ago, these savannahs gradually reverted to forested areas.

Numerous studies and reports confirm this. For further information, please refer to sources such as ScienceDirect, Google Scholar, and JSTOR.

Woody Encroachment: Challenges and Management

The park’s savannahs face forest encroachment due to increasing humidity and more balanced temperatures but remain vital ecosystems. This encroachment requires active management to maintain ecosystem balance.

The boundary between savannahs and forests in the Odzala-Kokoua National Park is clearly defined, and efforts to maintain this boundary include natural and controlled fire regimes. However, controlled fires are not always effective .

In some areas, numerous thickets or large, widely spaced trees already signal the beginning of forest colonization. Almost imperceptibly over the scale of a human life, all these savannah enclaves are gradually being encroached upon by forest and will eventually disappear if not actively managed (Multidisciplinary Digital Publishing Institute: Woody Plant Encroachment in a Seasonal Tropical Savanna).

Overall, the most effective bush encroachment control strategies in tropical and subtropical savannahs involve integrated approaches that combine mechanical, chemical, and fire management techniques. Continuous monitoring and adaptive management are essential for sustainable results.

The effectiveness of methods against savannah encroachment depends on climatic conditions, soil properties, and vegetation types. Additionally, the consequences of each method must be considered, including potential ecological and socio-economic impacts.

spotte-hyena_mbokoSpotted hyena: Immediately after crossing the Lékénie swamp forest on the wooden walkway at Mboko Camp.

Ecosystem Diversity: Where Savannahs and Tropical Forests Converge:

Odzala-Kokoua National Park presents a remarkable blend of ecosystems where savannahs and tropical forests converge, creating diverse habitats (s. Tropical Forest-Mosaic Forest). This diversity is crucial for biodiversity, hosting numerous bird, plant, and iconic animal species like the spotted hyena and forest buffalo.

These open plains, with unique ecological dynamics, serve as a crucial source of nutrients for the soil, differing from the lusher grasslands found in East Africa.

Remark: The first time I saw a spotted hyena in Odzala-Kokoua National Park, it was lounging in a puddle, contentedly gnawing on a forest buffalo haunch—clearly the largest hyena I'd ever seen. Subsequent sightings confirmed their exceptional size, a fact supported by wildlife studies attributing this to the unique prey and environmental conditions of the Congo forests.

Reference: Kruuk, H., & Turner, M. (2016). Ecological Factors Affecting the Size of Spotted Hyenas in the Central African Rainforests. African Journal of Ecology.

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White-fronted Bee-eaters perched on a corky branch near Mboko Lodge.

Fire-Resistant Plants: Nature’s Adaptations in the Savannah:

Plants in the tropical savannah demonstrate nature’s remarkable adaptability through specialized adaptations to fire-prone environments. Many species have evolved protective bark, similar to cork, which enables them to withstand and regenerate after fires.
 
Additionally, certain grasses produce seeds that germinate only after exposure to heat, ensuring their survival post-fire. These adaptations, characteristic of pyrophytes, are crucial for the plants' resilience and the continuation of life in the park's dynamic ecosystems.
 

Dembos: Vital Ecological Crossroads:

Dembos are seasonal marshlands acting as ecological connectors between terrestrial and aquatic ecosystems (just near Mboko Lodge, there's a Dembo that guests cross with a 4x4 game viewer to reach the Lékoli River cruise dock).

Elevated about two meters higher than the forest floor, they are crucial for water regulation and soil moisture retention. Dembos support a wide range of species, from amphibians and reptiles to migratory birds and various mammals (e.g. forest buffalos), enhancing biodiversity and ecological balance.

Termites: Earth's Tiny Titans

Termites, these industrious insects crucial to various ecosystems, truly deserve our admiration. Imagine a legion of tiny workers tirelessly maintaining the health and stability of their habitats, such as savannahs and tropical forests. Their relentless efforts help shape soil structure, enhance nutrient cycling, and support the overall balance of these environments, underscoring the essential role each species plays in sustaining ecological stability.

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Palmnut Vulture atop a termite mound at Mboko Lodge.


Without these remarkable engineers, the vibrant ecosystems of the savannah biome would not function as they do. At Odzala-Kokoua National Park, they are particularly abundant in the immediate vicinity of Mboko Lodge and characterize the landscape.

Namaqualand on South Africa's west coast is renowned for its vast termite mounds, which can reach up to 30 meters in diameter. Radiocarbon dating has shown that some of these active mounds are up to 34,000 years old—older than the earliest cave paintings in Europe. In contrast, the oldest known termite mounds, previously discovered in Brazil, are "only" 4,000 years old.

More interesting Facts about Termites:

 

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