Namibian Savanna woodlands

• Category: Grassland, Tundra, and Human Biomes.
• Geographic Location: Africa.
• Summary: A rich wildlife habitat, this savanna is bounded by deserts and shaped by climate extremes.

The Namibian savanna woodlands occur on Africa’s Great Escarpment, a high ridge that separates the Kaokoveld and Namib deserts from other interior biomes of southwestern Africa. The woodlands extend from north of the Fish River Canyon through Windhoek, the capital of Namibia, and on into southwestern Angola, spanning some 1,200 miles (1,940 kilometers) south to north. The biome is never more than about 200 miles (320 kilometers) wide.

There is a vast difference in rainfall across the region, ranging from an average of two inches (sixty millimeters) in the west to eight inches (two hundred millimeters) in the east, driven by the unpredictable thunderstorms during the October-to-March austral summer. While rainfall varies, the evaporation rate in the region exceeds ten feet (three meters) overall. Temperatures are predictable and can range from 16 degrees F (minus 9 degrees C) on cold winter mornings to well above 104 degrees F (40 degrees C) on summer afternoons.

The stony flatlands of the highland plateau, at about 3,281 feet (1,000 meters) above sea level, are intersected by the broken and dissected remnants of the escarpment. This yields massifs such as the Brandberg Massif, with its ancient White Lady rock painting, as well as the red rocks of the Spitzkoppe. The Kunene River is the only perennial river in the ecoregion, as the Swakop and Kuiseb Rivers are usually dry.

Flora

The diverse topography and associated soils of the Namibian savanna yield diverse flora. The ecoregion contains three vegetation types: mopane savanna, semidesert and savanna transition, and dwarf shrub savanna. Mopane trees (Colophospermum mopane) dominate the north, while the broad range of spurge (Euphorbia) plants are common in the semiarid zone to the west. To the southeast is the Kalahari xeric savanna biome. In each of these areas, the mopane grows together with Angolan green-thorn (Balanites angolensis subsp. welwitschii) in depressions and riverbeds, forming woodland stands. Also prominent in the mopane savanna are two species of genus Sesamothamnus, part of the sesame family Pedaliaceae. The Kaoko sesame bush (S. benguellensis) is found along the Kunene River, while the Herero sesame bush (S. guerichii) is spread across the mopane savanna. The Kaoko ceraria (Portulacaria longipedunculata) is typically abundant in the higher-altitude areas here.

The mopane savanna extends to the Brandberg Massif in the south, an isolated, remnant inselberg (island mountain) with an extremely high level of endemism. The massif supports more than one hundred vascular plant species that are endemic to Namibia, of which at least seven are found solely on the Brandberg: Felicia gunillae; Hermannia merxmuelleri; Lithops gracilidelineata subsp. brandbergensis, a subspecies of so-called living stones; Nidorella nordenstamii; Pentzia tomentosa; Brandberg plumbago (Plumbago wissii); and Ruellia brandbergensis, a species of wild petunia.

Gum arabic trees (Senegalia senegal) and umbrella-thorn acacias (Vachellia tortilis) are found mainly in the alluvial sands and silts along ephemeral rivers in the biome.

High diversity of the Commiphora genus of aromatic flowering plants, related to frankincense and myrrh, is particularly characteristic of both the mopane savanna to the north and the semidesert and savanna transition zone. To the south are Karoo shrubs and grasses such as three-thorn rhigozums (Rhigozum trichotomum), green-hair trees (Parkinsonia africana), water thorns (Vachellia nebrownii), shepherd's trees (Boscia albitrunca), stink shepherd's trees (Boscia foetida), and trumpet thorns (Catophractes alexandri), as well as smaller Karoo bushes, including Pentzia spp. and Eriocephalus spp. Tufted grasses, mainly Stipagrostis spp., are found scattered between the woody plants.

Fauna

The region is a center of faunal endemism, with seven endemic reptiles, including Albert's burrowing skink (Sepsina alberti) and the Nama padloper tortoise (Homopus solus). The Brandberg thick-toed gecko (Pachydactylus gaiasensis) is found only on the Brandberg Massif. Namibia has thirteen endemic bird species, which are most concentrated in the Kaoko escarpment, particularly the Herero chat (Namibornis herero). Among the mammals, Hartmann’s mountain zebra (Equus zebra subsp. hartmannae) roams the western sections of the Namibian savanna woodlands and is virtually endemic to Namibia.

Common iconic African wildlife also occurs here. Etosha National Park protects many such fauna in an area of 22,270 square kilometers (nearly 8,600 square miles) of Namibian savanna woodland surrounding the vast Etosha salt pan. Desert-dwelling African bush elephants (Loxodonta africana) move vast distances between water sources and foraging grounds in the biome. These are the larger of the two species of African elephants, but their tusks are invariably broken and stunted due to a mineral deficiency in the soils that makes the ivory brittle.

The region also supports the last unfenced black rhinoceros (Diceros bicornis) population in the world; individuals range over 965 square miles (2,500 square kilometers) and can go without water for up to four days. These behemoths have a flexible diet in this plant-deficient region but have a passion for euphorbias, despite their toxicity to most animals.

Black rhinoceros numbers plummeted in the 1970s through illegal poaching for their horns. The population fell from 70,000 in the 1960s to 2,500 individuals in 1995, where it has held steady for many years. By the 2020s, the numbers had climbed to just over 6,000 individuals. Northeastern Namibia faced some poaching, and conservation biologists removed the horns from some rhinos in an effort to reduce their attraction to poachers.

The region supports the unique black-faced impala (Aepyceros melampus subsp. petersi), a subspecies of the common impala that appears to be genetically distinct. Springboks (Antidorcas marsupialis), greater kudus (Tragelaphus strepsiceros), gemsboks (Oryx gazella), two species of zebra (Equus zebra and Equus quagga), and blue wildebeest (Connochaetes taurinus) also provide meals for the abundant large predator community, which includes southern African lions (Panthera leo subsp. melanochaita), African leopards (Panthera pardus subsp. pardus), and South African cheetahs (Acinonyx jubatus subsp. jubatus).

Human Settlement

Various Khoisan peoples have lived around Etosha for centuries. The Ovambo people named it Etosha, meaning “great white place,” in reference to the salt pan, which covers an area of approximately 1,900 square miles (4,800 square kilometers). The pan is hypersaline, which excludes plant growth, but soaks around the edges provide valuable freshwater for animals. It is generally empty but can fill in places during the summer, at which time it supports flocks of greater and lesser flamingos (Phoenicopterus roseus, Phoenicoparrus minor) and great white pelicans (Pelecanus onocrotalus).

The indigenous peoples have left their marks on the landscape through their majestic rock art and petroglyphs that reflected their spiritual beliefs. Places in the Namibian savanna woodlands such as Twyfelfontein have galleries of rock carvings of all manner of creatures, including some not native to the region. The rock-art galleries in the Brandberg depict similar standard images, but the meaning of the White Lady has confounded anthropologists for decades.

Europeans did not enter the region until Francis Galton (Charles Darwin’s cousin) and Charles Andersson passed through in 1851. The rinderpest plague in the 1890s devastated wildlife and livestock numbers in southern Africa, creating an impetus for German authorities to become more influential in the region. They created a livestock-free zone on the southern edge of the Etosha pan to minimize the risk of transmission of the disease. Governor Friedrich von Lindquist created Etosha National Park in 1907. At one time, Etosha was the largest conservation area in the world, covering more than 38,610 square miles (100,000 square kilometers), but it was reduced in 1967 to its current size.

Boreholes were sunk to open the land for pastoralism, but the names of the boreholes around Etosha, Stinkwater and Bitterwater among them, attest to the difficulties the early explorers faced in trying to open the region. Today, each of the major rest camps in Etosha occupies a former German fortified outpost, and many camps are named after the early explorers and the park’s creator. The waterholes at the Okaukuejo, Namutoni, and Halali camps are lit at night; they are among the best places in the world to see black rhinos, elephants, and lions.

Environmental Threats

The region faces a range of threats, irrespective of the protection offered by the Etosha National Park, the Brandberg Nature Reserve, and other nearby protected areas. Fencing along the 528-mile (850-kilometer) border of Etosha limits animal access to areas of fresh plant growth after localized rainfall, while fire and elephants are thought to have contributed to the alteration of the fauna community dynamics such that the area's blue wildebeest population had declined from more than 25,000 to just 2,300 by the late 1990s. However, in the 2020s, the population was about 7,000 in Namibia and considered stable. While the ecotourism benefits created via the presence of communal conservancies are large, these conservancies also can contribute to the problem of poaching.

Climate change could affect migration patterns of animals, forcing them to areas they do not usually travel to and then stranding them in areas unsuited to their dietary needs. Rising temperatures will further dry the arid areas, which could lead to species loss. It is likely that climate change will exacerbate the weather extremes of the region, reflected in both increased temperature and rainfall, making all species vulnerable.

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