CONSERVATIon

​Getting to know the secretive Nama-Karoo Biome​

FEB 16, 2023 | Written by BOTSOC NATIONAL. Photos by SAM JACK, TIM HOFMANN AND LOVEGREEN COMMUNICATIONS

Above: The Nama-Karoo Biome can offer the most incredible views over mountains and valleys . Photo by Sam Jack

The Nama-Karoo Biome has managed to keep many of its secrets. Because it is perceived as not as species-rich as the other biomes, it has been largely overlooked – and therefore under-researched. As a result, the way the Nama-Karoo ecosystems function is still not well understood as other more studied systems.

And yet this biome covers a vast area in the country, abutting on all the other major biomes here. It’s also home to a wide variety of animals, including the critically endangered Riverine Rabbit. Historically, this is also where extremely large, nomadic herds of game – notably springbok were found. These herds would have been essential food sources for indigenous peoples, most recently the |Xam. This means historical food and medicinal plant use would also be significant in the biome. That makes it all the more important to protect the Nama Karoo from the many threats it faces – from agriculture and mining to a changing climate.

Above: It may be a species-poor biome, but the Nama Karoo is still beautiful, and is home to many special species. Photo by Sam Jack

Where will you find the Nama-Karoo Biome?

The Nama Karoo is South Africa’s third-largest biome, accounting for around 20% of the total area in South Africa. In fact, it covers more than 135 000km² – making it larger than a country like Greece.

You’ll find the Nama-Karoo Biome on the central plateau of the western half of South Africa, occurring at altitudes of between 500 and 2 000m. It includes much of the Northern Cape, and northern parts of the Western and Eastern Cape. There’s even a section in the Free State, as well as the southern parts of Namibia.

Left: Upper Karoo Hardeveld in the Valley of Desolation in the Camdeboo National Park. Right: Bergbas (Osyris lanceolata). Photos by LoveGreen Communications

How the climate forms the biome

This semi-arid ecosystem survives with little rainfall and frequent droughts. During the late summer and early autumn months, the small amount of rain that does fall (most of the biome receives 200mm or less every year) gives life to the shrubs and grasses that occur here. But the ecosystem has evolved to endure the hot summers, with shrubs providing shade and protection to seedlings and smaller species from the boiling Karoo sun. During winter, these species can withstand extremely cold temperatures – especially at night.

A biome breakdown

The Nama-Karoo Biome contains three bioregions: The Bushmanland, Upper Karoo and the Lower Karoo Bioregions. There are also just 13 vegetation units. While it’s not as species rich as other biomes such as fynbos, you can still find more than 2 000 species here. Dwarf shrubs, grasses, shrubs, geophytes and herbs all occur here – growing mostly on lime-rich, weakly developed soil over rock.

Above: The Nama-Karoo Biome not only includes shrubs, but is also known for its grasses. Photo by Tim Hofmann

What makes it so valuable?

Don’t let the fact that it is mega diverse fool you. The Nama-Karoo Biome is still very special for many reasons. For one, it has interesting and intricate relationships with the six biomes that border it. That’s because in many instances, the transition between the Nama Karoo and those biomes around it are gradual – often gently transitioning over tens of kilometres (such as between the Nama Karoo and Savanna Biomes). Like much of the Nama Karoo, these pattens are still not well understood.

Above: In order to truly experience the Nama Karoo, take a trip to the wonderful Mountain Zebra National Park near Cradock. Photo: LoveGreen Communications

It’s also home to a number of species animals, including the Riverine Rabbit (Bunolagus monticularis). This is one of the world’s most threatened mammals – listed as critically endangered on the International Union for the Conservation of Nature’s Red List. The major threat to this rabbit (the only one in Africa which burrows) is ongoing habitat degradation, fragmentation as a result of poor land-use practices and hunting.

Mountain Zebra (Equus zebra) are also listed as vulnerable on the Red List – and are commonly seen in protected Nama-Karoo areas.

Above: Mountain Zebras are listed as vulnerable on the IUCN’s Red List, although they are protected in the Mountain Zebra National Park. Photo: LoveGreen Communications

Threats to our Nama Karoo

The Nama Karoo has become very degraded in parts. It is an important farming area – in particular for meat and wool-based small-stock farming. In fact, almost the entire Nama Karoo is grazed by livestock – mostly sheep and goats. But the soils here are highly erodible, which becomes extremely problematic when there’s overgrazing. What’s more, should this degradation continue over the long term, the land becomes increasingly unproductive – making it more economical for farmers to convert it to a crop the stock can forage on.

This threat is not new. As early as the 1930s the Department of Agriculture set out management guidelines which aimed at reducing stocking rates and encouraging rotational grazing. However, these threats to the landscape remain present today, given the economic importance of the region for cultivation and small-stock grazing.

Fire was never considered much of a threat in the Nama-Karoo Biome in years gone by. However, recent research has found that fires here have converted dwarf shrublands to grasslands, leading to the loss of many non-sprouter species. At the same time, more grasslands increase the risk of fires. As a result, fire could well change the Nama-Karoo landscape over time.

As with many other biomes, invasive plants are also threatening the biome. Species such as Prickly Pear (Opuntia aurantiaca) and Honey Mesquite (Prosopis glandulosa) have invaded parts of the Nama-Karoo.

Above: You’ll find Cussonia Paniculata, also known as the ‘Highveld Cabbage Tree’ in the Mountain Zebra National Park. Photo by LoveGreen Communications

The need for conservation action

Because the area is not well researched, it’s also not well conserved. Latest estimates suggest that less than 1% of the biome is formally protected. These include nature reserves such as the Karoo National Park and Mountain Zebra National Park (both SANParks reserves).

However, there are some initiatives in which non-profit organisations have partnered with landowners to bring about sustainable land management. The Endangered Wildlife Trust’s Drylands Conservation Programme, for example, is operating in the Nama-Karoo, encouraging responsible natural resource management as a way of protecting the integrity of ecosystems here. (And there’s a handy app for those interested in learning more about Nama plants).

The important role research plays here can also not be overstated. The Nama-Karoo Biome should be at the heart of the targeted research effort – so that this special, secretive area can start to reveal her many secrets.

Above: The soil of the Nama Karoo is often fertile – certainly more fertile than its neighbouring Fynbos Biome. Photo by Sam Jack

Further reading

Mucina, L. Rutherford, M.C. (2006) The Vegetation of South Africa, Lesotho, and Swaziland, Strelizia 19, South African National Biodiversity Institute, Pretoria, South Africa.

Dayarm, A. Harris, L, Grober, B. Van der Merwe, S. Rebelo, A. Powrie, L. Vlok, J. Desmet, P. Qabaqaba, M. Hlahane, K. Skowno, A. (2019) Vegetation Map of South Africa, Lesotho and Swaziland 2018: A description of changes since 2006, Bothalia, Vol 49 n.1, Pretoria, South Africa

Palmer, A.R. Hoffman, M.T. (1997) ‘Nama-karoo’ in Cowling, R.M. Richardson, D.M. Pierce, S.M. (Eds) Vegetation of Southern Africa, Cambridge University Press, Cambridge, UK.

Low, B. Rebelo, A. (1996) Vegetation of Southern Africa, Lesotho and Swaziland: A Companion to the Vegetation Map of South Africa, Lesotho and Swaziland, Department of Environmental Affairs and Tourism, Pretoria, South Africa

Du Toit, J. O’Connor, T. Van den Berg, L. (2015) Photographic evidence of fire induced shifts from dwarf-shrub- to grass-dominated vegetation in Nama-Karoo, South African Journal of Botany, Volume 101, Pages 148-152

Nama Karoo Plant App developed by EWT and partners. Available for iPhone and Android

Youngblood, D. (2004) Identification and Quantification of Edible Plant Foods in the Upper (Nama) Karoo, South Africa, Economic Botany, Vol. 58, Supplement, pp. S43-S65

Morris, D. (2018) Before the Anthropocene: human pasts in Karoo landscapes, African Journal of Range & Forage Science, 35(3-4), 179–190