Scripta Varia

Erica verticillata, from extinction to restoration

Anthony Hitchcock[*]

Forerunner

The Kirstenbosch conservation programme in the 1970s and 1980s was pioneered by Curator John Winter and focussed on establishing collections of threatened species in pots in the Kirstenbosch Collections Nursery. Each collection was established and cared for by horticulturists dedicated to specific target families such as Proteaceae and Ericaceae. While this initiative is to be commended it was severely limited due to space and inability to preserve enough gene pool in pot collections. In most cases, threatened species collections were soon reduced to single clones through attrition with little conservation value and in all too frequent instances lost altogether.

In 2002, the author was appointed to the position of Nursery and Living Collections Manager which included responsibility for threatened species. The limitations of conservation pot collections and the need to revise the conservation programme were identified. To this purpose, a new conservation strategy was developed for Kirstenbosch. This comprised an integrated approach to include ex situ and in situ conservation activities. The focus was placed on sound genetic-based ex situ conservation collections and, where possible, in situ restoration at secure and ecologically sustainable natural area reserves. Fortuitously, the South African National Biodiversity Institute (SANBI) signed an agreement with the Royal Botanic Gardens, Kew in 2000 to become a partner and contributor to the Millennium Seed Bank Project. From this time, the primary ex situ collections were housed in seed banks and these were augmented by collections in dedicated threatened species stock beds and pots. The latter were used as source material for restoration projects mainly on Cape Flats Sand Fynbos (CFSF) where a critical need was identified to conserve the vegetation type and the ecosystem therein. Thereafter, the conservation strategy led by Kirstenbosch evolved beyond simple species conservation to include sustainable habitat and ecosystem conservation and management. Naturally, this required partnerships with other conservation organizations, primarily the Environmental Resource Management Department (ERMD) for the City of Cape Town and the South African National Parks. Some years later, SANBI was tasked to develop South Africa’s response to the Global Strategy for Plant Conservation. Numerous researchers were included from within SANBI and other academic and conservation organizations to develop South Africa’s Strategy for Plant Conservation (SASPC). This was completed and endorsed by the Minister of Environmental Affairs in 2015. The relevant South African target pertinent to this paper is based on the GSPC with amendments decided upon at the workshops.

GSPC: Target 8: At least 75 per cent of threatened plant species in ex situ collections, preferably in the country of origin, and at least 20 per cent available for recovery and restoration programmes

SASPC: Target 8: At least 60% of threatened plants in ex situ collections, preferably in the country of origin, and available for recovery (restoration) programmes, with 1% in active reintroduction programme.

The South African Strategy amended the global targets to what was decided to be manageable in South Africa bearing in mind the large numbers of threatened species and capacity available. The target of 20% available for recovery and restoration programmes was deemed too ambitious in the South African context and possibly meaningless since plants ‘available for restoration’ is not equal to them being in active restoration. One percent was decided upon based on the number of species already in in-situ conservation and the considerable resources and expertise required to manage this. Additionally, Kirstenbosch was also the only Botanical Garden in SANBI doing in situ conservation.

The following case study examines the integrated approach to conserving Erica verticillata (whorl heath), and documents ex situ conservation at Kirstenbosch and in situ conservation at three areas on the Cape Flats.

Introduction   

Erica verticillata is a flagship for threatened species at Kirstenbosch and in SANBI and is unique in the annals of plant conservation in South Africa (Hitchcock, 2003). Its recovery and restoration is an interesting case study and may provide useful lessons in plant conservation. It is a beautiful, sturdy species growing to between 1.5-2 m in height, but old specimens have been recorded to be up to 3 m tall. It produces beautiful maroon or light pink, tubular flowers arranged in neat whorls organized in distinct groups up the principal stems and near the tips of sturdy branches. Peak flowering is from January to March, but plants produce some flowers intermittently throughout the year. The flowers attract sunbirds, bumblebees, hawk moths, bees, and beetles that come to sip the nectar the flowers provide as reward to pollinators. The specific epithet, from the word ‘verticillatus’, is descriptive of the whorled (verticillate) arrangement of the flowers.

It used to grow in Cape Flats Sand Fynbos (CFSF) on the lowlands of the Cape Peninsula from the Black River to Zeekoeivlei (Oliver & Oliver, 2000). Herbarium records indicate that it grew in a narrow, 3 km-wide corridor between the main road and the M5 freeway from the Black River cottages near Mowbray in the north, at Rondebosch, Newlands, Claremont and Kenilworth as far as Wynberg (Figure 14.1). A single, isolated record from Kalk Bay (Thompson, 170 in PRE) might be suspect. The written record suggests that it may have occurred as far south as Zeekoeivlei (Adamson & Salter, 1950).

The rather superficial information on herbarium sheets and in the literature suggests that this species preferred seasonally damp, acid, sandy soils near rivers and wetlands. Agricultural and urban development that occurred as Cape Town expanded resulted in the destruction of its natural habitat. It is an attractive plant with long flowering stems and was regularly sold as a cut flower, being one of the few plant species to flower in profusion during the mid-summer (January-March) months (Gibbs, 2014). The last herbarium specimen collected from the wild dates to 1908 and was collected by Dümmer (Dümmer, 210 in NBG). More recent herbarium records in South Africa are specimens of plants growing at Kirstenbosch in 1943 (Henderson, 1669 in NBG) and from a cultivated plant growing in the Pretoria district (Repton, 5698 in PRE). The whorl heath also appears on the Bergvliet Primary School badge (Hilton-Taylor, 1996b).

After the Second World War, an entirely new suburb of Cape Town was established to provide accommodation for ex-servicemen. The Bergvliet Housing Scheme attracted many young families and soon a modern primary school was built in 1949 ready for the first term of 1950 (Bergvliet Primary School, 2013). The school chose the whorl heath as the focal point of its badge because it was a very popular plant common in the Bergvliet area until about 1948. It was regarded as possibly extinct in the wild by 1950 (Adamson & Salter, 1950) and was listed extinct in 1996 (Hilton Taylor, 1996a). Hilton Taylor classified a species to be extinct if it was not found in its natural habitat after repeated searches. This category was also used for a taxon that no longer occurs in the wild but survives in at least one form in cultivation or in a seed bank. Contemporary classifications record it as extinct in the wild (Raimondo et al., 2009).

The recovery of Erica verticillata

During the early 1980s, the Kirstenbosch Erica horticulturist, Deon Kotze, was actively searching for and establishing pot collections of threatened ericas (Hitchcock, 2003). His attempts to find remnant populations of Erica verticillata in the few remaining Cape flats habitats in the southern suburbs of Cape Town were unsuccessful. Fortunately, the 1984 Kirstenbosch Scholar, Dawid von Well, recognized the species from herbarium specimens and brought back flowering samples and cutting material from Erica plants growing at Jan Cilliers Park, also known as Protea Park, in Groenkloof, Pretoria. Collections of fynbos were established in Protea Park during the 1960s by Curator J.E. Repton (Grobler, 2013). This was most probably the same as the specimen lodged in the herbarium by Repton in 1961 (Repton 5698 in PRE). It was confirmed as Erica verticillata by Dr. E.G.H. Oliver and propagated for the collection. A few years later, a mature stand of this species was discovered by the Kirstenbosch Head Foreman, Adonis Adonis, growing in a derelict bed behind the Braille Trail.

It is assumed that the specimen growing at Kirstenbosch and lodged in the herbarium by Henderson (Henderson 1669 in NBG) originates from the Louisa Bolus collection made in 1917 because it is the only record of this species being collected from habitat in the Kirstenbosch Garden plant records. Furthermore, there is a 1920 record of planting ericas that like wet habitats in the Harry Bolus Orchid Garden to provide some shade protection to the ground orchids. The Bolus Orchid Garden was situated where the Braille Trail exists today and where the old Erica verticillata plants were found (Figure 14.2).

In addition to accession numbers, registered cultivar names were given by the British Heather Society to each collection to distinguish them from one another (see Appendix). There are subtle differences between each cultivar such as flower colour, corolla tube length and density of flower arrangement, size of plant, and density of foliage. These differences are also evident on the herbarium collections.

The Pretoria collection was named ‘African Phoenix’ and the Kirstenbosch collection was given two cultivar names to distinguish the dark pink form, ‘Adonis’, from the light pink form ‘Louisa Bolus’. The latter cultivar honours Louisa Bolus, the first Curator of the Bolus Herbarium, who made the first and only wild collection of the whorl heath for Kirstenbosch. She is recorded to have collected seed from the Wynberg Flats on 1 May 1917 (Hitchcock, pers. obs.).

The search for lost collections of the whorl heath was continued by the author in 2000 and was an exercise in detective work. The existence of additional collections was revealed with assistance from Dr. Oliver, members of the British and American Heather Societies, botanic gardens, Erica growers in Europe, and internet searches. Through this process, collections were added from the following: Belvedere Palace Garden in Vienna – ‘Belvedere’; Tresco Abbey Gardens on the Scilly Isles – ‘Tresco Abbey’; the private Erica collection of ‘Doctor Violet Gray’ via the British Heather Society – ‘Doctor Violet Gray’; Monrovia Nursery in California – ‘Cherise’; the Royal Botanic Gardens, Kew (RBG, Kew) – ‘Harry Wood’. More recently, another form has been identified. This specimen comes from a small market garden nursery, Heidegartnerei Grunberg in Dresden, which is specialized in Erica. It was being sold at a market in East Berlin. This was bought by Erica nurseryman Helmut Heidl and passed on to Kirstenbosch. It was given the registered name, ‘Dresden’. Nine confirmed collections have been found to date all of which have been allocated cultivar names by the British Heather Society (Appendix 1). The author is currently investigating the origin of another distinct form supplied by Helmut Heidl which may well be the tenth form recovered. Four of the cultivars, ‘African Phoenix’, ‘Adonis’, ‘Louisa Bolus’, and ‘Belvedere’ have been used in restoration programmes (Hitchcock, 2013; Grobler, 2013).

The role of the Belvedere Palace Garden in conserving Cape ericas and threatened species goes back a long way and is unsurpassed in botanic gardens’ history. Belvedere Gardens is part of a group of botanical gardens and parks in Vienna that collectively fall under Österreichische Bundesgärten (Austrian Federal Gardens) and include the famous Schönbrunn Gardens. Two gardeners, Francis Boos and George Scholl, were responsible for many plant collections made in the Cape between 1786 and 1799 for Emperor Joseph II of Austria (Gunn & Codd, 1981). Boos was evidently the leader of the expedition. He was a botanist as well as a gardener whereas Scholl was a working gardener with little scientific knowledge. Emperor Joseph II sent them to make collections of tropical plants from Mauritius, but bad weather forced their ship to shelter at the Cape of Good Hope and their stay turned out to be longer than planned (Nelson & Oliver, 2004). They made numerous collections of South African plants and even went on a brief collecting trip with Francis Masson (Gunn & Codd, 1981). Boos stayed at the Cape for a year and then went on to Mauritius leaving Scholl behind to continue collecting. Boos returned to the Cape in 1788 and stayed for only a few months before returning to Vienna in July 1788 with a large collection of specimens and living plants. Scholl stayed at the Cape for twelve years mainly because he could not get passage on a ship that would transport his plant collections. Scholl was aided in the Cape by Colonel Robert Jacob Gordon, Commandant of the Dutch Garrison at the Cape. Gordon gave him protection, assisted him with his field excursions and allowed him to grow his plants in his garden, often referred to in literature as ‘the Gordon’s Garden’, which was situated on what is now Prince Street in the suburb known as Gardens (Garside, 1942; Gunn & Codd, 1981). Many plants were established here, and Scholl collected seed from them. From time to time, Scholl sent shipments of dried bulbs and seeds to Vienna, of which four shipments are recorded in the Cape Archives from 1790 to 1792. They were first shipped to the Austrian Consul in Holland who had them transported up the Rhine and then overland to Vienna. Scholl was finally able to return to Vienna in 1799 taking with him a large collection of living plants and seed, including species of Erica. Scholl was rewarded for his efforts by being promoted to the post of Superintendent to the Gardens of the Belvedere Palace (Garside, 1942). Staff at the Austrian Federal Gardens believe that the ericas at the Belvedere Palace Garden date back to the Boos and Scholl collections, as there is no evidence of other collections being made. Michael Knaack, Head of the Department of Botanical Collections at Belvedere, asked his predecessor who had been working in the gardens since the 1930s for further information on this issue. He remembered the collections manager before him saying that the collection had always been there. Therefore, the erica collection dates at least as far back as the nineteenth century and therefore quite conceivably originates from the Boos and Scholl collections. The Belvedere collections has representatives of various Cape Proteaceae and at least 67 ericas of which two are extinct in the wild, two critically endangered, three endangered, two vulnerable and three rare.

These original collections at Belvedere Palace Gardens appear to have been nurtured for over 200 years through all the political turmoil of wars and conquest. Some members of the Heather Society of Great Britain doubt that these collections could have survived the ravages of war and particularly the bombing at the end of the Second World War. Indeed, most of the collections at Belvedere were destroyed at the end of the war when the glasshouses were damaged by a bomb falling in the centre of the Reservegarten. Many plant collections survived however, because they were purposely duplicated and moved to other gardens and glasshouses, so it was possible to reduce the risk and to save most of the species. The erica collection was evidentially moved to the Alpengarten (Alpine Garden) where there is an Erdhaus (earth house). An earth house is a house where earth is used as an additional building material for a significant proportion of the covering of the wall or ceiling construction. In the earth house, the earth acts as an insulating layer that protects against cold, rain and wind. This is apparently how the erica collection survived the last winter of the Second World War in Vienna.

Conservation

There is much debate and some scepticism within the community of botanic gardens and academic, conservation and botanical research organisations over the conservation value of keeping collections of wild species in botanic gardens or at private growers (Cadman, 2016). However, experience with the whorl heath demonstrate that maintenance of a conservation collection can play an important role in the preservation of a species and may in some cases contribute to conservation programmes, at least for charismatic species.

The best way to conserve a species is in its natural habitat where it is subject to natural ecological systems (Hitchcock et al., 2012). The Cape Town area is 2460 km² in extent and has 19 vegetation types, 6 of which are endemic, 10 are critically endangered, 3 are endangered and 4 are vulnerable. There are 3250 plant species in the core Cape Town area of which 450 species are threatened and included in the Red List: 49 of these are locally extinct and 13 are globally extinct, the greatest number for any city in the world (Holmes et al., 2012).

Restoration of many threatened species on the lowlands of the Western Cape is complicated by the fact that most threatened species occur in threatened habitats that are often small, fragmented and compromised by edge effect. Erica verticillata occurs in the Cape Flats Sand Fynbos (CFSF) vegetation type, which is classified as critically endangered (Figure 14.3). Humans have damaged and destroyed over 85% of CFSF due to urban expansion of the City of Cape Town with more than half of this occurring in the last 50 years, and the vegetation type has over 110 threatened Red List plant species (Raimondo et al., 2009).

The South African National Conservation Target for the CFSF vegetation type is 30% (Mucina & Rutherford, 2006). The amount left has declined from 16% in 2009 (Stipinovich & Holmes, 2009) to 13.4% in 2016 of which only 2% are conserved in nature reserves, while half of this is degraded and in poor condition (Holmes & Pugnalin, 2016). As of 2017, only 11% CFSF remains, of which only 4% can be considered natural vegetation and potentially restorable, with the remainder being highly degraded (i.e. unploughed, but there is a legacy effect of alien vegetation having altered the ecosystem quite radically). Alien woody species such as Acacia saligna invade fynbos and, in most cases, form dense, impenetrable stands which dominate and replace the natural vegetation. They drastically change the natural community structure causing the reduction in species diversity and water resources. They increase the fuel loads that result in too many intensely hot fires, which are detrimental to the recruitment of many fynbos species. Acacias produce large numbers of hard-coated seeds that are long-lived and germinate in profusion after fire and outcompete natural vegetation (P. Holmes, pers. comm.). The remnants of this vegetation type are severely fragmented and most conserved areas – Rondevlei Reserve (9.2ha), Meadowridge Common (6.0ha) and Rondebosch East Common (5.1ha) – are too small to provide viable habitats. There are only two areas large enough for restoration, namely Blaauwberg Nature Reserve and Tokai Park. Rondebosch Common and Youngsfield are too transformed and Kenilworth Racecourse Conservation Area[2] (42ha) is privately owned without any official conservation status. Attempts to establish a conservation management agreement with the racecourse owners have not succeeded to date (Hitchcock et al., 2008). The abovementioned status of CFSF illustrates the dire situation when attempting to restore threatened species to their natural, historical habitat.

Restoration programmes for Erica verticillata

The rediscovery of the whorl heath excited interest amongst some conservationists to re-establish it in its natural habitat. Three restoration attempts were undertaken at three sites between 1994 and 2008. These include Rondevlei in the False Bay Nature Reserve, Kenilworth Racecourse Conservation Area (KRCA) and at the Tokai Section of Table Mountain National Park. These were the only areas within or near the species’ natural historical range where it was possible and suitable to undertake restoration.

Rondevlei Nature Reserve

Dalton Gibbs, Conservation Manager for the City of Cape Town, made the first attempts to reintroduce the whorl heath at Rondevlei Nature Reserve in 1994. The challenge was to discover a suitable place for planting, as so little habitat information was recorded, other than that it occurred “near moist areas”. He planted 20 specimens of the cultivar ‘African Phoenix’ grown in 1kg bags supplied by Kirstenbosch, in a transect starting at the drier sandy areas across a range of habitats ending in the wetland. Only one plant survived in the intermediate, moist area, indicating that this species might prefer the marginal areas between the dry and wet soils. More were planted in 1995, 1997, and 1998 (Hitchcock, 2003). These established well, reaching maturity and attracting several pollinators, including Cinnyris chalybeus subsp. chalybeus (southern double-collared sunbird), Lepidoptera: Sphingidae (hawk moths) and Xylocopa spp. (carpenter bees). Despite this, they did not produce seed, and it was concluded that the clone ‘African Phoenix’ was self-sterile. In 2001, two more clones, ‘Adonis’ and ‘Louisa Bolus’, were planted at pollination distance to each other to enable seed production. These additional clones were successful in setting viable seed. Seed was collected and germinated in the Rondevlei nursery in 2005 (Wilman, pers. comm.) The first ecological fire – a prescribed burn – was put through the population of 150 plants on the 27th March 2013. The fire behaviour observed at Rondevlei suggests that this species has an unexpected strategy of suppressing fire and a complementary flowering strategy to ensure survival. When fire passes through the population, the plants burst into flame as the leaves torch up and then, unexpectedly, the fire subsides, leaving behind relatively unscathed plants. The fire incinerates the flammable leaves but burnt skeletons of branches appear to be fire-resistant, remaining intact, unlike the companion species which are burnt to the ground. The dead plants clearly mark out where the ericas once stood, perhaps providing semi-shade and wind protection for the seedlings. It is also suggested that restricting the seed to the original distribution may be essential to this species which has ecotonal habitat requirements (Gibbs, 2014).

It is assumed that the flowering strategy of Erica verticillata is as follows. It flowers from mid-summer to early autumn (January to April) which is the fire season in fynbos. Successive whorls of flowers are produced. When the first set of flowers mature the next set is in bud. There are often three groups of flowers arranged up the stem. Fires normally occur in late summer by which time the first seed capsules have matured, while the second set is still flowering. The seed is retained in protective capsules, which open within a few hours of the fire, scattering seeds beneath the skeletal parent plant. It has been observed that recruiting seedlings survive better where they are given protection from the elements by nurse plants. In the absence of fire, the seeds are released when ripe at the end of summer. The first record of post-fire recruitment of Erica verticillata from seed was observed in 2015 (Gibbs, pers. comm., 2015).

The seedlings had to contend with vigorous regrowth from competing plants such as Stenotaphrum secundatum (H. Walter) Kuntze (Buffalo Grass) and Psoralea pinnata L. (Fountain Bush). It is difficult to be sure, but it appears that seedlings might have been overwhelmed by competing plants. This demonstrates that a functioning ecosystem is critical to the success of restoration programmes. The role of herbivory in controlling competition at Rondevlei is being studied through a pilot project to reintroduce eland (Tragelaphus oryx) (Cape Times, 2015). This project started in 2016 and initial observations are positive: eland are selective in what they browse, feeding on grass and woody vegetation, but ignoring the Erica plants (Cape Times, 2015).

Kenilworth Racecourse Conservation Area (KRCA)

The site is regarded as the best and least disturbed example of CFSF remaining on the southern suburbs of Cape Town.[3] In 2004, 100 plants comprising 3 clones, 50 ‘African Phoenix’, 25 ‘Adonis’ and 25 ‘Louisa Bolus’, were planted within 100m of each other at Kenilworth (KRCA) in a seasonally wet depression. Young plants in 1kg bags, propagated from cuttings, were planted in mature vegetation to protect them from the summer heat and wind. Eighty per cent of these plants survived and have flowered profusely every year. Seedling recruitment has been observed in open patches near the parent plants. Cape Nature organized a controlled burn in an adjacent section of the KRCA in March 2005. A second population was established in a moist area adjacent to the east. Plants grown in 50cc re-usable plastic Unigrow® propagation plugs, and in 1kg bags, were planted in mid-winter, June 2005 (Hitchcock, 2006). The plants from plugs all died during the summer, probably because they were too exposed to the desiccating summer winds and heat. Thirty per cent of the plants grown in 1kg bags planted amongst grasses survived. It is surmised that the plants in bags survived better because they were protected by re-sprouting grasses that were growing in situ. It has been observed that ‘nurse plants’ shelter young plants from desiccating summer wind and by partially shading the plants, keeping them cooler and in better condition. It is speculated that plants grown in plugs do not have enough root mass to support the young plants through the first summer whereas those in larger containers have a larger root mass to sustain them. This is based on monitoring other young plants in restoration where 1kg container plants survived better than those planted from plugs, although the surviving plug-grown plants outperformed the plants grown in 1kg bags in the long term.

Tokai Park

This site, which has been under pine plantations for the past 100 years, is now being managed to protect and conserve its endangered vegetation type CFSF. Most of the restoration at Tokai is passive, relying on natural regeneration after felling the pines and a restorative fire to flush the seed bank. However, several species designated as extinct or critically endangered (Raimondo et al., 2009) have been reintroduced. This is the case with Erica verticillata for which a reintroduction programme began at Tokai in 2004 managed by Kirstenbosch, South African National Parks and the Millennium Seed Bank Project. The first planting took place in the Soetvlei wetland which was recovering after clearing (Hitchcock & September, 2016). The plants grew well but were being chewed down to ground level by Otomys irroratus (African vlei rat) and swamped by vigorous wetland plants, such as Cyperus spp. (Sedges). A new site higher on the slope was identified where competing plants were less likely to swamp the young ericas. The area was also more exposed, which we hoped would allow predators such as raptors to control the rodents. Further rodent control involved the relocation of snake species Pseudaspis cana (mole snakes) and Bitis arietans (puff adders) which had been rescued from adjacent residences and stables. The ericas established splendidly, with the aid of predators or not, and have become a feature admired by visitors to Tokai Park.

The most extensive planting to date of 5,000 plants of whorl heath was planned along the Prinskasteel wetlands in 2008. The wetlands are bordered by pine plantations, but there was enough natural area to make an experimental planting along the southern fringe of the wetlands stretching for 200m (September, 2010). Three clones, ‘Adonis’, ‘Belvedere’ and ‘African Phoenix’, were selected as the best seed producers (Grobler, 2013). Sunbirds are common in the area so we hoped that they would pollinate and result in the formation of a significant seed bank. The planting was done in rows, 1m apart comprising 15, 10 and 15 plants of the 3 clones respectively. The rows were perpendicular to the stream edge from the water’s edge into the dry areas. The restoration of the whorl erica in the wetlands was more successful than anticipated despite the gradient where some plants were planted in drier areas. There was one instance of careless herbicide application when subcontractors controlling invasive Rubus also sprayed some of the ericas, killing 20 per cent of plants – the total mortality was 40 per cent. This, together with other challenges such as fire belts being cut through the restoration stands, highlights the need for coordinated management, efficient communication and knowledgeable supervision. The plants survived best in the marginal zone between dry and wet and grew to be larger and more robust on the wetter end. Plants which were further from the wetland were smaller, and most of the plants in the driest zone died. The vigorous plants in the wet marshy areas did less well, being overwhelmed by wetland species. ‘Belvedere’ did not do as well as the other two clones, being smaller and less robust when planted. The experiment showed that even though some sedges outcompeted the whorl heath in the wettest habitat, and aliens did so in others, the restoration was still comprehensive and extensive over the area. The variety of pollinators visiting the ericas was astounding, with far more pollinators than just the birds which had been expected to be attracted by the blossoms. Apart from Anthobaphes violacea (orange-breasted sunbird) and Cinnyris chalybeus (southern double collar sunbird), other visitors noted included wasps (Hymenoptera), carpenter bees, Cape honeybees (Apis mellifera subsp. capensis), hawk moths, and some small beetles. Subsequently, plantings have been made along the Prinskasteel canal, and in two other wetlands at Tokai, with the whorl heath establishing far better than most other species attempted, perhaps because wetlands buffer against the summer droughts (which have been particularly severe recently) better than the drier sands typical of sand fynbos. This is corroborated by the fact that a planting outside of the wetlands was a total failure. Restoration at Tokai is a finely balanced process and the public were asked to keep out of the restoration areas to allow the recovery process to develop with as little human impact as possible. However, promoting awareness is critical and the public must be informed. This is in line with Target 14 of the GSPC: “The importance of plant diversity and the need for its conservation incorporated into communication, educational and public-awareness programmes” (Convention on Biological Diversity, 2010; Raimondo, 2015). SANParks and the Friends of Tokai Park (a public volunteer group affiliated with the Wildlife Society of South Africa (WESSA)) selected an area between two of the entrances where some of the threatened species could be planted to showcase the restoration work at Tokai. Funding was provided by the Old Mutual Two Oceans Marathon via the Table Mountain Park Honorary Rangers. The area is called the Tokai Restoration Trail and includes interpretation boards explaining the restoration process, reasons and the management plans. The trail was designed by a local landscape architect and includes pathways and a boardwalk over the wet areas. A range of CFSF species are planted, ten of which have threatened status: extinct in the wild, critically endangered, endangered, and vulnerable. The trail was planted by Tokai Park staff, Friends of Tokai Park, Kirstenbosch National Botanic Garden, and Millennium Seed Bank staff, and was opened by Park Manager Paddy Gordon in September 2013.

Lessons learned when restoring Cape Flats Sand Fynbos

Fynbos is a fire-adapted ecosystem requiring periodic burning. In the absence of fire, fynbos is gradually outcompeted by woody coppicing species such as Searsia lucida. Fynbos thrives on infertile soils and fire is the mechanism by which senescent plant material is removed and nutrients are recycled into the soil. Fire is a crucial trigger that resets the ‘successional clock’. It provides the stimulus for dormant seeds to germinate and the opportunity for many annuals, short-lived perennials and bulbs to grow, flower and set seed during times of abundant nutrients and sunlight. They complete their short life cycles, returning to the soil as larger shrubs overwhelm them, and remain dormant until the next fire. The optimal fire cycle for fynbos is 10-20 years (Kraaij & Van Wilgen, 2014). Shorter fire cycles can wipe out slow-maturing species, while other species start dying when intervals become too long. Restoration of fynbos species needs to include fire in the management protocol. To determine when the project to restore the whorl heath to the wild may be considered successful is problematic. IUCN Red List rules state that reintroduced plants must produce viable offspring before they can be counted as mature individuals (IUCN Standards and Petitions Subcommittee, 2016). In other words, after two generations, all flowering plants which are producing seed can be counted as mature individuals and used in the population assessments. Erica verticillata has self-incompatible clones so in this case the viability of the F1 generation must be checked before assessing the success of the species in the restoration project. In most cases the second natural generation after planting would qualify as a success, but in the case of the whorl heath, it is suggested that a third generation is required in order to ensure that the F1 is fertile and sustainable. In addition, given the threats of recruitment competition from natural and alien species in a habitat recovering from disturbance which includes pine plantations, root disturbance by dune moles, excessive herbivory or lack thereof and variances in climate, it is recommended that successful re-establishment of a species in fynbos requires the reintroduced population to survive three fire cycles. In order to down list Erica verticillata from ‘extinct in the wild’, an assessment will have to be made of the number of plants that exist after three generations; whether the population is stable, declining or increasing; how fragmented the populations are; and the level of conservation protection afforded to the areas of restoration.

Conclusion

Several lessons have been learned in the process of restoring Erica verticillata and many of these are pertinent to active species restoration on CFSF. The ex situ conservation approach alone is insufficient and therefore an integrated approach including in situ conservation is essential if possible. Restoration of a species on its own is not good enough. A sustainable restoration programme needs to include restoration and sustainable management of the remaining ecosystem, which in this case includes fire. Success in restoring a species depends upon a healthy stand of the vegetation type being in place, along with pollinators and other animals and soil fauna and flora required for maintaining the system. If this is not in place, steps must be taken to restore the missing components. Any imbalance in this system, such as an explosion in the population of vlei rats, as happened in Tokai Park, might result in one component becoming a problem rather than having a beneficial influence. The destructive and positive role of herbivory needs to be explored further as this might be a crucial factor in success or failure (Cape Times, 2015). Finally, the entire system must be managed holistically, with fire belts and alien control programmes incorporated into areas targeted for species-specific restoration. Conservation of the rich Cape flora is an enormous challenge, particularly given the increased demand for land and resources, and the effects of climate change. This is especially true of the Cape lowlands and CFSF where Erica verticillata originates. At the time of writing, large numbers of plants are on the brink of extinction on the Cape lowlands. We will lose these species, and many more, unless these endangered habitats are conserved as a matter of urgency. Erica verticillata therefore plays a crucial role as a flagship species to create an awareness of the general plight of our vanishing flora within the City of Cape Town and beyond.

Erica verticillata is one example of many attempts to conserve and restore threatened species under the direction of the GSPC. Yet the survival of this species, despite more than 35 years of concentrated efforts to bring it back from the brink of extinction, is uncertain. The weakest link is that the existing clones are only housed at Kirstenbosch National Botanical Gardens. Since April 2018 there has been no dedicated horticulturist looking after the Kirstenbosch Erica collection. A recent visit to the collection with molecular systematists in March 2019 revealed that already one of the clones is incorrectly labelled and more than 50% of Ericas in the pot collection are unlabelled. The survival of Botanical Gardens ex situ pot collections depends upon good and continuous curation. Efforts are being made by the author with assistance from Cape Town conservation staff, Erica researchers and other botanical gardens to establish backup collections in Europe and in the City Conservation nursery under MOUs.

The critically endangered status of CFSF vegetation type is another serious threat. The horseracing industry in South Africa is depressed and there are repeated attempts by the owners of the Kenilworth Racecourse Conservation Area to develop the natural areas in efforts to maximize profits. There have been attempts by Cape Nature to get the owners of Kenilworth Racecourse to sign a MOU to declare the central natural area a Section 23 Nature Reserve under the Protected Areas Act. While negotiations are still in process development proposals are being made including draining the area for underground parking and providing services to the conservation area. If they get approval to drain the area the whole conservation area will be compromised.

The Tokai Park is also under threat. Even though it has been handed over to SANParks for restoration and management there is considerable public pressure from a group called Parkscape who are demanding the retention of the remnant pine plantations and thereafter rotational replanting of pine trees to keep the area shaded for their recreation. This despite the forestry company having declared the area uneconomical for plantations (Figure 14.4).

In terms of the threats to E. verticillata and other CFSF species the current and increasing trend of land invasions around Cape Town poses a risk to these systems. Alien vegetation, although controlled in many areas, continues to be a long-term threat, especially Acacia saligna (Port Jackson) which has an enduring seed bank.

Another threat to these systems is the expertise and passion which is needed to sustain them into the future. Dalton Gibbs, senior manager for Environmental Resource Management Department (ERMD) for the City of Cape Town, is not convinced that there are sufficiently trained and motivated conservation staff to sustain specialised habitat types such as CFSF (Gibbs, D., pers. com).

Fortunately, seed of Erica verticillata has been harvested and banked at the MSBP, but only from two parents. There is scope for further conservation work and research on this species. Dr. Mike Pirie, specialist in organic, molecular and evolutionary botany focussing on Erica, is keen to sequence the available clones to investigate them further as part of ongoing conservation research.

Acknowledgment

The author acknowledges Sibbaldia[4] as the primary source for this paper.

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END NOTES

[*] Kirstenbosch National Botanical Gardens, SANBI, South Africa.
[2] www.krca.co.za
[3] www.krca.co.za
[4] More specifically, the corresponding article by Hitchcock & Rebelo (2017) published in Sibbaldia: The International Journal of Botanic Garden Horticulture, 17:101-120. The Royal Botanic Garden Edinburgh, Edinburgh. 

 

 

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