The Cape Floristic Region is home to one of the richest floras in the world. Within an area of just 90 000 km2 there are some 9250 species of flowering fynbos plants, some 70% of which are restricted to the region. Fynbos is the major element of this region, contributing more than 80% of its species. The region also includes renosterveld, karroid shrubland, thicket and forests . Fynbos is not only famous for its remarkable diversity, but also the beauty of many of its wildflowers. It is found at the southern tip of Africa in roughly a crescent shaped belt from Vanrhynsdorp in the north, southwards to the Cape Peninsula and eastwards to Port Elizabeth. Fynbos is largely restricted to the distribution of the parallel sandstone and quartzitic formations of the Cape Fold Mountains and the extensive areas of sand and limestone along the coast. Here it thrives on coarse-grained soils that are low in nutrients, especially nitrogen and phosphorous. It is predominantly found in the winter rainfall region of the Cape, although there are areas in the Eastern Cape, where fynbos thrives, that are characterised by all year round rainfall. The main reason for the exceptional diversity in fynbos is not an unusually high concentration of species in a particular site, but rather the high proportion of turnover in species between sites. This is the result of the high rate at which species give way to each other across environmental and geographical gradients. So what makes fynbos really special is its exceptionally high numbers of localised species, often restricted to a single, small area, sometimes less than 1 km2. Grootbos alone is home to at least seven endemic species.
Fynbos and fire
Fynbos is a fire-adapted vegetation that requires regular burning for its persistence. In the absence of fire, fynbos is gradually replaced by thicket species. It thrives on infertile soils and fire is the mechanism that recycles precious nutrients from old moribund growth into the soil. Fire in fynbos is far from a disaster, but rather a crucial trigger that resets the fynbos ‘succesional 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 seed during times of abundant nutrients and sunlight. They complete their short life cycles, returning to the soil as the larger shrubs overwhelm them, and remain dormant until the next fire. The optimal fire cycle for fynbos is between 10-14 years. Shorter fire cycles can wipe out slow maturing species, while species start dying when intervals become too long.
The unique flora of the Cape is under severe pressure from human activities. The fynbos of the mountainous areas is generally well protected in a considerable reserve network established to ensure plentiful supplies of clean drinking water for the growing human population below. Unfortunately, the same cannot be said for the lowlands. Here, centuries of intensive agriculture have resulted in monocultures over almost all of the more fertile areas. On the Agulhas Plain, some 25% of lowland fynbos has been transformed by agriculture, and of the remaining habitat, the majority is invaded to some degree by Australian wattles and other invasive species. The wattles were planted in order to stabilise coastal dune fields during the mid-twentieth century and have subsequently spread into the fynbos, outcompeting and throttling the indigenous flora. Critically almost all of the lowlands are in private ownership and only about 5% is formally conserved. Other threats include rapidly escalating urbanization, especially coastal resort development, drainage of wetlands, inappropriate fire regimes and unsustainable flower harvesting. Socioeconomic issues are amplifying the effect of these threats. For generations the plight of poor rural communities has been largely ignored. In many of the towns and villages poverty is rife and as much as half of the inhabitants are unemployed. At Grootbos our conservation initiatives are focused on providing sustainable nature based livelihoods for local people as well as protecting and restoring our unique natural heritage.
Fynbos on Grootbos
For more than a decade Grootbos staff have been busy with a unique long-term vegetation study, quite possibly the most detailed ever undertaken in the fynbos region. The plant survey of our reserve has included all seasons and all stages of post-fire succession. At latest count the number of positively identified, herbarium-catalogued plant species on Grootbos was a staggering 765 species on just 1800 hectares. Eighty three of the species found are species of conservation concern, while a total of six species new to science have been recorded. The deeply significant ecological role of fire in fynbos was emphasised by the way the checklist jumped from 680 species to 750 after the huge 2006 blaze that swept through Grootbos – 70 new species for our list as a result of post-fire successional processes. The reserve is home to a wide variety of vegetation types including critically endangered Overberg sandstone fynbos, endangered milkwood forests, afromontane forests tucked away in fire proof kloofs, locally rare Agulhas limestone fynbos restricted to the limestone outcrops of the area, Overberg dune strandveld near the coast and wetland vegetation.
New plant species first recorded on Grootbos
A total of six species new to science have been recorded during our vegetation survey of the Reserve. These are briefly described below. For a full description of these and other plants on Grootbos contact us to order our "FIELD GUIDE TO THE FLORA OF GROOTBOS NATURE RESERVE AND THE WALKER BAY REGION".
Erica magnisylvae (Ericaceae)
This species was first found by Sean Privett on Grootbos during the original vegetation survey of the Reserve in the winter of 1997. It was described by Ted Oliver of the Compton Herbarium who named it with reference to its discovery on Grootbos; magnisylvae = of the large forest in classical Latin. It has so far only been recorded on Grootbos with an outlying population on the damp slopes above Platbos Forest to the south east.
Cliffortia anthospermoides (Rosaceae)
At first sight this species may be mistaken for a member of the genus Anthospermum (Rubiaceae), hence its species name anthospermoides. It was first discovered by Anna Fellingham on Grootbos Nature Reserve in Overberg dune strandveld vegetation in 1996. Only four populations are known, all on or in close vicinity to Grootbos and only the population on Grootbos is protected.
Lachenalia lutzeyeri (Hyacinthaceae)
This species was first collected by Heiner Lutzeyer on the upper slopes of Witkransberg after a small fire in November 2004. It only flowers in the early summer following fire and is presently only known from the type locality on Witkransberg on Grootbos.
Pterygodium vermiferum (Orchidaceae)
First recorded on Grootbos on the path up to Swartkransberg at an altitude of 385m by Heiner Lutzeyer in 2003. Subsequent collections have been made on these western slopes of the mountain at three separate sites about 260 m apart, a second population is located along the road between Stanford and Gansbaai and a third population is at Die Kelders at an altitude of 50 m. The total known area of extent of this species measures just 5.5 by 3.0 km along an L-shaped range, the majority of which is conserved within the Grootbos Reserve!
Capnophyllum lutzeyeri (Apiaceae)
This species has only ever recorded on Grootbos.It was first located following the 2006 fire on acidic soils. No plants were found in subsequent searches suggesting that it is a short-lived, fire-induced, species.
Dasispermum grandicarpum (Apiaceae)
It is known only from Grootbos, where it was first collected by Heiner Lutzeyer in 2007 in fynbos vegetation that had burnt the previous year. No plants could be located in subsequent searches suggesting that the species may be a short-lived species, germinating, flowering and dying in the first year following fire.