Forests of South Africa

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.

Toni touches base with the Southern Cape

Written by Jo-Anne King. Photos by Jo-Anne King, Antonia Xaba and Joao De Barros.

On Monday, representatives of the Outramps CREW (Custodians of Rare and Endangered Wildflowers) and BotSoc Garden Route Branch were very excited to host BotSoc General Manager Antonia Xaba and show her a prime example of Southern Cape flora.

Above: Sandra Falanga, Jo-Anne King, Jenny Potgeiter, Antonia Xaba, Di Turner and Pauline Cloete enjoy the Cape Dune Molerat Trail, Wilderness, Garden Route. Photo: Joao De Barros.

The Cape Dune Molerat Trail in Wilderness was selected by Di Turner, Outramps CREW team leader, as it provided both high diversity in flowers and a vigorous bit of exercise in a short time frame. Anyone who knows this CREW group knows that the hustle up the path is also very important!

Top: Gladiolus rogersii in bloom was outstanding all along the trail. Photo: Antonia Xaba. Above: Garden Route Branch Treasurer Pauline Cloete and Chair Jo-Anne King (kneeling) stop to photograph a wild Freesia. Photo: Antonia Xaba.

Buchus on show included Agathosma ovata (False Buchu) and Agathosma apiculata (Garlic Buchu), with beautiful bulbs Freesia leichtlinii subsp. alba (White Freesia) and Gladiolus rogersii (Riversdale Bluebell) peppering the entire walk.

Top: The fluffy flowers of Tarchonanthus littoralis. Photo: Antonia Xaba. Above: Hyobanche are endemic to South Africa. Photo: Jo-Anne King.

Whether over the fairylike white bells of Erica formosa, the satin sheen of Struthiola ciliata (Rope Capespray), or the fluffy tufts of Tarchonanthus littoralis (Coastal Camphor Tree) in flower, the members of Outramps CREW never fail to observe and praise the wildflowers they find, diligently photographing the delicate petals for iNaturalist/SANBI. Much excitement was raised by the sight of a neon orange, silky haired Hyobanche, an unusual parasitic plant endemic to South Africa.

Above: Outramps CREW love finding rare plants such as this parasitic Hyobanche. Photo: Antonia Xaba.

Many thanks to Di Turner for faithfully organising every week’s successful Outramps CREW outing – and to the whole group for spreading the love of indigenous wildflowers among the youth of the Garden Route.

 

Above: The formidable Di Turner takes a break under Erica sessiliflora. Photo: Antonia Xaba.

Five reasons to welcome an Aloe into your garden

As winter comes to South Africa the nights draw in, the locals wrap up warm and batten down the hatches. Driving rain and gale force winds lash the Cape at regular intervals, snow caps the mountains and frosts line Highveld gardens. As winter arrives it is time up and down the country for many Aloe species to come into bloom. South Africa is home to 125 different Aloe species with many more hybrids bred for cultivation. So what makes these beauties so worthwhile to grow? The BotSoc Blog is here to take a closer look.

They add warmth and colour to the winter garden

Above: The Aloe Garden at Garden Route Botanical Gardens in full bloom. Photo: Zoë Poulsen

When the winter days are short and the weather is cold, Aloes cannot fail to bring warmth to your garden with their spectacular blooms. Their torch-like blooms come in many shades of yellow, red, green, orange and everything else in between against the dark winter skies. They look particularly spectacular when planted en masse. Check out the Matthews Rockery at Kirstenbosch NBG, the Succulent Rockery at Walter Sisulu NBG or the Aloe Garden at Garden Route Botanical Gardens for inspiration.

They come in all shapes and sizes

Above: Aloe hybrids in the display garden at Rooiklip Nursery, Swellendam, Overberg. Photo: Zoë Poulsen

No matter the size of your garden or outdoor space, there is always an Aloe that will fit whether you garden in pots on a small balcony or have a sweeping expanse of garden. The Tree Aloes, now in their own genus Aloidendron, grow to form huge and many branched specimens with Aloidendron barbaraeforming a trunk up to three metres in diameter. Hollow trunks of particularly large specimens of Aloidendron dichotomum are sometimes used as natural refrigerators. In contrast, the widely cultivated Aloe variegata and many others grow easily in small pots. This species was one of the first Aloes to be successfully cultivated in Europe.

They are waterwise

Above: Aloe marlothii in habitat. Photo supplied by Eugene Moll.

We live in a water scarce country, gardening with the need to use water sustainably so we have sufficient for when the next drought comes around the corner. One of the keys to waterwise gardening is selecting the right plants that will survive with minimal or no additional summer watering. Aloes are perfect waterwise additions to the garden. Their succulent leaves make them highly drought tolerant and they require minimal maintenance once established.

They attract wildlife into the garden

Top: Aloe speciosa. Above: Aloe huntleyana. Photos: Zoë Poulsen

As South Africa’s cities grow, coastal housing developments sprawl and habitat loss from urbanisation is ongoing, gardens are becoming increasingly important places for our wildlife. Well planted indigenous gardens can support a plethora of different species, supporting pollinators and acting as corridors through urban areas for wildlife. The rich nectar from many Aloe species support bees, butterflies and colourful sunbirds that make beautiful visitors to the indigenous garden.

They have a plethora of different medicinal and cosmetic uses

Above: Aloe arborescens in full bloom in the Matthews Rockery, Kirstenbosch NBG. Photo: Zoë Poulsen

Members of the genus Aloe have a plethora of different medicinal uses. In South Africa Aloe ferox is most widely used in medicinal and cosmetic products. When an Aloe leaf is cut, the juice oozes from the cut leaf and this can be used in first aid treatment of burns. Aloe juice from Aloe arborescens was used in the treatment of irradiation burn victims of Hiroshima. Extracts from the leaves have since been shown to have anti-inflammatory, antibacterial, anti-ulcer and wound healing effects.

So what are you waiting for? Why not give a home to one of these extraordinary plants in your outdoor space? Happy gardening!

Paintbrushes of the Veld: Spotlight on Haemanthus

Article and photos by Zoë Poulsen

Known for its bizarre paintbrush-like flowers, the genus Haemanthus is one of the most famous of the Amaryllidaceae family. When autumn comes to the veld and little else is in flower, these strange blooms emerge from the dry earth where they have been lying dormant over the summer months. The genus is endemic to Southern Africa and found only in Namibia, South Africa, Lesotho and Swaziland with the main centres of diversity being central and southern Namaqualand and the Knersvlakte around Vanrhynsdorp. Some species are widespread and occur across a wide variety of different habitats whereas others are specialists adapted to a specific habitat niche. Some Haemanthus from winter rainfall areas flower in profusion after fire has cleared overstorey vegetation. Most members of the genus grow in colonies, a phenomenon perpetuated by the peduncles leaning towards the ground under the weight of the seeds as they ripen leading to germination around the parent plant.

Above: Haemanthus albiflos growing in afrotemperate forest habitat on the Garden Route.

Haemanthus albiflos is one of only three evergreen species of Haemanthus. It was first described and illustrated by N.J. Jacquin in 1797 from material collected from the Cape. This species is distributed from Stilbaai eastwards to northern KwaZulu Natal where it grows in coastal and riverine forest, thornveld and valley bushveld in light to deep shade. Flowering takes place from May to October.

Top & Above: Haemanthus coccineus in flower and fruit on the Bokkeveld Escarpment.

Haemanthus coccineus is the most widely distributed members of the species. It is found from southern Namibia southwards to the Cape Peninsula, eastwards to the southern Eastern Cape and inland to Sutherland and Ladismith. This species is found in habitat as varied as its distribution, growing on soils derived from sandstone, granite, quartzite, shale and limestone. Haemanthus coccineus is often found in rocky habitats where it commonly grows in the shade of boulders. In contrast it is also found growing on coastal dunes. Flowering occurs from February to April.

Above: Haemanthus barkerae flowering in habitat.

My first encounter with the intense pink inflorescences of Haemanthus barkerae was a lonely flowerhead lying on the ground after having likely been removed by foraging baboons. This species is endemic to South Africa’s Northern Cape, distributed from Louriesfontein to the Hantamsberg and northern Tanqua Karoo where it grows on heavy clay soil. Haemanthus barkerae was only recently described, previously being thought to be part of Haemanthus pumilio until it was revised by Dee Snijman in 1984. Flowering takes place from March to April.

Above: Haemanthus canaliculatus flowering after fire in Hangklip Sand Fynbos.

Haemanthus canaliculatus is another range restricted member of the genus, known only from the Overstrand coast between Rooiels and Betty’s Bay. It was first collected in Betty’s Bay by a Mrs. M Brunt in 1943, but not described until 1966 by botanist Margaret Levyns in the Journal of South African Botany. The species epithet of Haemanthus canaliculatus refers to the deeply channelled leaves that typify this species. It is a wetland specialist, growing in peat in Hangklip Sand Fynbos. It flowers in profusion after fire, growing in dense colonies. Haemanthus canaliculatus is Endangered on the Red List of South African Plants as a result of housing development reducing the number of populations.

Above: Endangered Haemanthus pumilio flowering in habitat.

Last but not least is the diminutive Haemanthus pumilio, its species epithet meaning ‘dwarf’ in reference to its low growing habit. This species was first described in 1797 by N.J Jacquin having been introduced to RBG Kew by Francis Masson who collected it at an unrecorded locality at the Cape. Haemanthus pumilio is endemic to the lowlands around Stellenbosch and Paarl where it grows on gravelly clay flats in renosterveld vegetation. Much of its habitat has been lost as a result of urbanisation and transformation for agriculture and it is now only known from a handful of sites. Flowering takes place from March to April and the seeds are thought to be water dispersed. Haemanthus pumilio is listed as Endangered on the Red List of South African Plants.