Today is Earth Day and the theme for 2021 is Restore Our Earth. Three days (20-23 April 2021) of live streaming events connected to the Earth Day campaign can be found here. In this post I highlight South Africa’s major biomes to draw attention to the diversity that, although diminishing, we still have.
All South Africa’s biomes are under threat in multiple ways and it seems fitting to honour what we still have as a reminder that much needs to be done to restore and protect them.
Transformed by urbanization, this tract of land (near the coast in the southern Western Cape province) is denuded of its natural vegetation diversity and is contaminated with discarded waste
A biome can be defined as being “a large community of vegetation and wildlife adapted to a specific climate”. Globally, the five major types of biomes are aquatic, grassland, forest, desert and tundra (nationalgeographic.org). Although there are different ways of classifying biomes with some systems being more or less broad than others, all biomes are determined by climate (rainfall and temperature), and affected by other factors that include geography (latitude and longitude) and local attributes such as mountain barriers, altitude, surface water and soil types.
In South Africa, in addition to freshwater and marine biomes, nine terrestrial biomes are recognised: Grassland, Savanna, Forest, Fynbos, Succulent Karoo, Nama-Karoo, Albany Thicket, Indian Ocean Coastal Belt and Desert (http://pza.sanbi.org/vegetation).
With grassland pictured in front of a patch of mistbelt forest, the KwaZulu-Natal Midlands landscape beyond is highly modified by human activity, and includes tree plantations, farmlands and artificial dams
Biomes are not necessarily discrete entities and there may be transitional areas between different zones. Biomes may be extremely localized because of specific conditions – for example, small forest patches can occur within grassland biomes.
Within a classified biome there are various and distinct vegetation types. Forests, for example, can be montane, scarp, mistbelt, sand, coastal, lowland riverine and so on.
A patch of natural forest in the KwaZulu-Natal Midlands
In South Africa forests occur mostly in relatively small patches within other biomes. Forests require sufficient rainfall and protection from fire. In total, forest covers only 0.1 % of the land surface in South Africa, and less than 0.25% of the broader southern African region, being the smallest biome in the African subcontinent.
The largest biome in the region is the Savanna biome covering over one-third of the land in South Africa and 46% in southern Africa, including in Botswana, Namibia and Zimbabwe. Savanna has a grassy ground layer and an upper layer of woody plants, ranging from Shrubveld through the more intermediate Bushveld to Woodland.
A giraffe strolls through Acacia Savanna at Mkhuze Game Reserve in KwaZulu-Natal. This photo was taken in an unusually green summer prior to several years of severe drought across the region
Savanna grasses require summer rainfall. Most Savanna grasses and plants can regenerate after fire. The Savanna biome accommodates the widespread farming of grazing livestock. For a map of the southern African Savanna biome see here.
A small group of cattle is herded along a road in an Acacia Savanna area neighbouring Mkhuze Game Reserve. Many homesteaders are highly dependent on small-scale vegetable and livestock farming for subsistence in under-resourced rural communities with high levels of unemployment
Another biome of significant size in South Africa is the Grassland biome. It is widely exploited for the purposes of beef, dairy and wool production and grasslands have been significantly replaced with maize and other crops such as sorghum, wheat and sunflowers. Consequently the rich biodiversity of grasslands has been significantly diminished. For a map of the South African Grassland biome see here.
Early summer wild flowers in grassland in the KwaZulu-Natal Midlands
Farming in the Grassland biome near Harrismith in KwaZulu-Natal. I took this photo from the car while travelling on the N3 freeway
The second largest biome in South Africa is the Nama-Karoo biome that occurs on the central plateau in the western part of the country. For a map see here.
The low scrubby vegetation typical of the Nama-Karoo biome seen here in the Karoo National Park
The Nama-Karoo biome is a semi-desert arid region with low summer rainfall where the limey soil is shallow and poorly developed. The large herds of springbok and other wild animals are long gone, and now the region sustains sheep and goat farming where overgrazing can be a problem on fragile lands.
When one takes a more micro view of the Nama-Karoo vegetation the diversity to be discovered is staggering
Further west than the Nama-Karoo biome is the Succulent Karoo biome. Although soil types are similar in the two biomes the rainfall patterns are significantly different. Whereas the Nama-Karoo has low and variable summer rainfall, the Succulent-Karoo is determined by very low winter rainfall and arid summers. For a map of the Succulent Karoo biome see here.
A spring-flowering succulent ‘vygie’ at Gamkaberg Nature Reserve in the Little Karoo region of the Western Cape
Some areas, such as the Ai-Ais Richtersveld Transfrontier Park, are situated in the transitional zone between summer and winter rainfall regions and so plants from different biomes may intermingle. Adding to the complexity is that the mountain ranges have an effect on the meagre rain that does fall, so that seaward-facing slopes (even though inland) receive more precipitation than inland-facing slopes. Resulting microclimates and other conditions can be so specific that some plants are endemic to very narrow locations.
Given the complexities of climate patterns at the Ai-Ais Richtersveld Transfrontier Park, I cannot be sure but I am guessing that the vegetation in the above photo is in a transitional zone between the Succulent Karoo and Nama-Karoo biomes
Whatever the vegetation types, the rugged landscapes of the arid Ai-Ais Richtersveld Transfrontier Park are spectacular
Although vast areas of South Africa are arid and classed as semi-desert, only a small section in the north-western part of the Ai-Ais Richtersveld Transfrontier Park is classed as true desert. This desert area is in the Gariep (Orange) River Valley in the Springbokvlakte area on the border with Namibia. See the map here. Most true desert in southern Africa is in Namibia – but that will have to wait for another post.
The biome unique to South Africa that is perhaps best known is the Fynbos biome, which includes both the true Fynbos and the Renosterveld vegetation types. Fynbos plants occur in a small area in the south western part of the Western Cape province, yet they are incredibly numerous and diverse. For a map see here. It is estimated that 7000 species of plants occur in the Fynbos vegetation type and 1000 in the Renosterveld type.
A glimpse of some typical Fynbos vegetation
Threats to the Fynbos biome include urbanisation and development (Cape Town and major coastal resorts occur in the Fynbos biome). Other threats include fertiliser use, expansion of crops, invasive alien plants and fire. Although Fynbos is fire adapted, fires in the wrong season (for example spring instead of late summer) and too frequently so that plants cannot set seed result in the elimination of plants. Fire in the Fynbos biome is a hot topic currently following the recent fires on Table Mountain that caused widespread damage, including to the University of Cape Town’s Jagger Library and the destruction of thousands of items in its African Studies Collection.
Another example of plants and flowers in the Fynbos biome
The Albany Thicket biome – also known as Subtropical Thicket – comprises several thicket types including Spekboom thicket, and it is characteristic of many parts of the Eastern Cape. For a map see here.
Two klipspringers hiding in thicket at the Gamkaberg Nature Reserve
Elephants feeding in thicket at the Addo Elephant National Park
The ninth terrestrial biome in South Africa that I just touch on here is the Indian Ocean Coastal Belt biome, which stretches 800 km down the coast from the border with Mozambique to the Kei River mouth in the Eastern Cape. See map here.
Part of the Maputaland Coastal Belt in northern Zululand in KwaZulu-Natal, coastal vegetation can be seen inland of the Kosi Bay estuary with vegetated dunes forming a barrier between the estuary and the ocean
The coastal vegetation is a mosaic of open grassland often dotted with small trees, including palms, and forest, woodland and wetland vegetation. The coastal plain is sandy with coastal dunes being a feature along sections of the coast.
Nguni cattle grazing on grasses in the Maputaland Coastal Belt that forms part of the Indian Ocean Coastal Belt
I had thought to include the aquatic biomes in this post, but I will hold that over for another post. Highlighting the nine terrestrial biomes in South Africa that all require protection and differing degrees of restoration seems a fitting way of acknowledging Earth Day.
Also included in the Earth Day campaign’s list of suggested actions that we may choose to play a role in, is to plant a pollinator garden (https://www.earthday.org/actions/plant-a-pollinator-garden/).
And on the subject of planting for pollinators, I was astounded to read in Nancy Lawson’s Humane Gardener blog her most recent post titled ‘Butterflies:1 Bullies:0’ in which she describes how a homeowner’s association (HOA) in Maryland in the US had been demanding that specific homeowners under their jurisdiction remove their pollinator garden that had been flourishing and treasured for 18 years. By removing the garden the HOA demanded that the homeowners rip out all the plants and flower beds and replace them with turf grass, i.e. lawn. The HOA spent thousands of dollars in legal fees while making these bizarre demands.
The homeowners (Nancy Lawson’s sister and her husband) decided to fight back, and after an ongoing saga over three difficult years the heartening outcome is a House Bill recently passed by the Maryland General Assembly codifying the right for gardeners in developments controlled by HOAs to be wildlife-friendly, plant-friendly and environmentally conscious. To read this astonishing tale, see https://www.humanegardener.com/butterflies-1-hoa-bullies-0/
Boon, Richard. 2010 (2nd ed.). Pooley’s Trees of Eastern South Africa. Durban: Flora & Fauna.
Earthday.org. 2021. Earth Day 2021: Three Days of Climate Action. https://www.earthday.org/earth-day-2021/
SANBI. [n.d.] Vegetation of SA, South African National Biodiversity Institute (SANBI). http://pza.sanbi.org/vegetation
Siyavula. [n.d.] Biomes. Siyavula Technology-Powered Learning. https://intl.siyavula.com/read/science/grade-10-lifesciences/biosphere-to-ecosystems/08-biosphere-to-ecosystems-03
Posted by Carol