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Forests of South Africa

Jul 27, 2020  |  Written by Zoë Chapman Poulsen. Photos by Eugene Moll, Francois du Randt and Zoë Chapman Poulsen.

Introduction

Above: Sand Forest in the False Bay section of iSimangaliso Wetland Park, KwaZulu-Natal. Photo: Francois du Randt.

As the climate crisis has escalated, an increasing global focus has been placed on forests due to their potential for climate change mitigation through carbon storage. Some researchers advocate widespread global tree planting as a solution, despite many of the world’s ecosystems not being tree dominated. There has been a long held and misconstrued idea that we need to plant more trees in South Africa to ‘save the earth’, with forest mistakenly perceived as one of our most threatened ecosystems.

Despite this strong international focus, research and conservation planning around South Africa’s forests have been highly neglected, with the country having few dedicated forest ecologists. Few realise that South Africa’s forests are some of the most species rich temperate forests worldwide. However, indigenous forest only covers 0.56% of South Africa’s landmass. Within South Africa’s extraordinary range of ecosystems, only a tiny proportion of the country provides the necessary ecological conditions to support indigenous forest.

Forest Biodiversity & Biogeography

Above: Northern Afrotemperate Forest in Royal Natal National Park, KwaZulu-Natal. Photo: Zoë Chapman Poulsen.

South Africa’s forests have a highly fragmented distribution, extending in an archipelago of patches from the south-west to the north-east. Forest species richness and diversity increases in a gradient from the southwest to the northeast. Forest extends inland to the Great Escarpment and northwards to Oorlogskloof, Nieuwoudtville. The most extensive forests are found around Knysna and Tsitsikamma.

Variation in climate, topography, altitude and latitude have resulted in a diversity of forest types. The vegetation map of South Africa, Lesotho and eSwatini recognises 12 forest groups divided into 26 forest types. Forest patch size varies with some as small as 1 ha. Research has shown that these smaller forest patches still support the full suite of ecological processes necessary for ecological integrity and are equally important in conservation planning and practice.

Forests and Fire

Above: Southern Afrotemperate Forest in Orange Kloof, Table Mountain after fire. Photo: Zoë Chapman Poulsen.

Within the fynbos and grassland biomes, one of the key determinants of forest distribution is the presence, absence and frequency of fire. Forest is often found growing in natural fire refugia such as in steep sided kloofs, boulder screes or deeply weathered rock cracks. Forest will rarely burn, only with exceptionally high temperatures and windspeeds or drought. Hot and more frequent fires will lead to a forest patch decreasing in size, whereas infrequent fires or long term absence of fire will lead to the forest patch growing in size. This can lead to significant changes in forest distribution over relatively short time scales.

Conservation status and threats facing South Africa’s forests

Above: Tall Sand Forest in Tembe Elephant Park, KwaZulu-Natal. Photo: Francois Du Randt.

Most of South Africa’s forests are currently managed as conservation areas, with a government mandate in place to protect all forests on private, communal and state-owned land in line with the National Forest Act (Act No 84 of 1998). The 2018 National Biodiversity Assessment recognises South Africa’s forests as one of several ecosystem types that provide disproportionate benefits to people relative to their size, including water purification, nutrient cycling, carbon storage, storm protection, recreation and food.

However, some of South Africa’s forests are impacted by wood harvesting for fuel and building materials as well as extensive bark harvesting from certain species for medicinal use. This can lead to eventual death of the tree if the tree is fully ring barked. South Africa’s mangrove forests are classed as Critically Endangered due to habitat loss from harbour development. Riparian gallery forests in Mpumalanga are also threatened due to water abstraction.

Afrotemperate Forest

Above: Afrocarpus falcatus in Southern Afrotemperate Forest in Nature’s Valley, Garden Route. Photo: Zoë Chapman Poulsen.

Afrotemperate forest has two vegetation units: Southern Afrotemperate Forest and Northern Afrotemperate Forest. Southern Afrotemperate Forest is distributed from the Cape Peninsula eastwards to the Eastern Cape, with the main centre of diversity being the Knysna-Tsitsikamma region. This forest type is usually tall and multi-layered and is dominated by yellowwoods (Afrocarpus falcatus and Podocarpus latifolius). Cunonia capensis is present in deep gorge habitats. Northern Afrotemperate Forest is distributed from the Free State and Lesotho northwards to Limpopo, where it is found in small patches in kloofs at higher altitudes. Taller trees present include Celtis africana and Halleria lucida.

Coastal Forest

Above: Coastal dune forest at Twinstreams, Umtunzini, KwaZulu-Natal with an understorey of Isoglossa woodii. Photo: Eugene Moll.

Coastal forest comprises Southern Coastal Forest and Northern Coastal Forest. Southern Coastal Forest is found in the Western and Eastern Cape, including coastal dune systems. These forests are dominated by Milkwood (Sideroxylon inerme) from Llandudno on the Cape Peninsula eastwards to Nature’s Valley. Further east the species richness increases with dominants including Brachylaena discolor and Euclea natalensis. Northern Coastal Forest is found predominantly along the coastline of KwaZulu-Natal and is relatively species rich. It mostly grows on coastal plains and stabilised coastal dunes.

Mistbelt Forest

Above: Mistbelt forest with near endemic Podocarpus henkelii in KwaZulu-Natal. Photo: Eugene Moll.

Mistbelt forests are relatively species rich afrotemperate forests that differ through the presence of subtropical floral elements. Southern Mistbelt Forest is found in the Eastern Cape and KwaZulu-Natal, in fire shadow habitats on south and southeast facing slopes at higher altitudes. Podocarpus henkelii is a near endemic to this vegetation type. The vegetation is dominated by a range of deciduous and semi-deciduous trees such as Celtis africana and Calodendrum capense. Northern Mistbelt Forest is found in Limpopo and Mpumalanga in east facing fire refugia such as moist and sheltered kloofs. There are a number of endemic taxa including Cryptocarya transvaalensis.

Scarp Forest

Above: Scarp forest in the gorge of the Umtamvuna River, KwaZulu-Natal. Photo: Eugene Moll.

Scarp forest is species rich and structurally diverse with a significant number of endemic taxa. It is found in the Eastern Cape, KwaZulu-Natal, Mpumalanga and eSwatini, either on coastal platforms or in deep gorges. This vegetation type was once home to the extinct in the wild Encephalartos woodii, today known only from a few individuals housed in botanical gardens.

Sand Forest

Above: Allelopathic borders in Sand Forest in Tembe Elephant Park, KwaZulu-Natal. Photo: Francois du Randt.

Sand forest is found from KwaZulu-Natal northwards into Mozambique, predominantly in Maputaland. This forest type has a tall forest canopy layer with a relatively depauperate ground layer. Much of this forest has been cleared historically for subsistence agriculture and grazing. Uncontrolled extraction of wood for fuel is also a significant problem. Sand Forest is therefore Critically Endangered.

Mangrove Forest & Swamp Forest

Above: Swamp forest with Barringtonia racemosa flooded at Twinstreams, Umtuzini, KwaZulu-Natal. Photo: Eugene Moll.

Mangrove forest and swamp forest are both azonal vegetation units. Swamp forest is found at low altitudes in KwaZulu-Natal and the Eastern Cape on muddy waterlogged soils. The tree Raphia australis is endemic to this vegetation. Mangrove forests are found in coastal estuaries in the Eastern Cape and KwaZulu-Natal, making them the highest latitude coastal mangroves in the world. This vegetation is Critically Endangered due to historic habitat loss from harbour development.

Further Reading

du Randt, F. (2018) The Sand Forest of Maputaland, South African National Biodiversity Institute, Pretoria, South Africa.

Mucina, L. Geldenhuys, C.J. (2016) ‘Afrotemperate, subtropical and azonal forests’, pp. 585-615 in Mucina, L. Rutherford, M.C. (Eds) The Vegetation of South Africa, Lesotho and Swaziland, Strelitzia 19, South African National Biodiversity Institute, Pretoria.

Venter, E. (2011) Trees of the Garden Route: Mossel Bay to Storms River, Tien Wah Press, Singapore.

Von Breitenbach, F. (1974) Southern Cape Forests and Trees, The Government Printer, Pretoria, South Africa.