The Nama-Karoo covers most of the vast central plateau region of the Western and Northern Cape. The area forms a transition between the Cape flora to the south, and the Savannah in the north. Many of the plant species of the Nama-Karoo also occur in the Savannah, Grassland, Succulent Karoo and Fynbos biomes.
Nama Karoo Biome occurs on the central plateau of the western half of South Africa, at altitudes between 500 and 2,000m, with most of the biome failing between 1 000 and 1,400m. It is the second-largest biome in the region
The Nama Karoo rain fails in summer, and varies between 100 and 520 mm per year. This also determines the predominant soil type – over 80% of the area is covered by a lime-rich, weakly developed soil over rock. Although less than 5% of rain reaches the rivers, the high erodibility of soils poses a major problem where overgrazing occurs.
South Africa Holiday: Distribution of the Nama Karoo Biome in South Africa
The dominant vegetation is a grassy, dwarf shrubland. Grasses tend to be more common in depressions and on sandy soils, and less abundant on clayey soils. Grazing rapidly increases the relative abundance of shrubs. Most of the grasses are of the C4 type and, like the shrubs, are deciduous in response to rainfall events.
The amount and nature of the fuel load is insufficient to carry fires and fires are rare within the biome.
South Africa Holiday: ‘Three Sisters’ in the Nama Karoo
The large historical herds of Springbok and other game no longer exist. Like the many bird species in the area – mainly larks – the game was probably nomadic between patches of rainfall events within the biome. The Brown Locust and Karoo Caterpillar exhibit eruptions under similarly favourable, local rainfall events, and attract large numbers of bird and mammal predators.
Less than 1% of the biome is conserved in formal areas. The Prickly Pear Opuntia aurantiaca and Mesquite Prosopis glandulosa are the major alien invader species. Urbanization and agriculture are minimal, and irrigation is confined to the Orange River valley and some pans.
South Africa Holiday: Dwarf shrubs of the Nama Karoo (Augrabies Falls National Park, Northern Cape)
Most of the land is used for grazing, by sheep (for meat, wool and pelts) and goats, which can be commensurate with conservation. However, under conditions of overgrazing, many indigenous species may proliferate, including Threethorn Rhigozum trichotomum, Bitterbos Chrysocoma ciliata and Sweet Thorn Acacia karroo, and many grasses and other palatable species may be lost. There are very few rare or Red Data Book plant species in the Nama Karoo Biome.
South Africa Holiday: Quiver Tree in the the Nama Karoo (Augrabies Falls National Park, Northern Cape)