Fynbos


Overview of the plant life of the Scarborough area

Fynbos, Strandveld and Seashore Vegetation

By Nick Helme

Scarborough lies near the southern tip of the Cape Peninsula, an area renowned for its exceptionally high plant diversity, and for the high proportion of species that are endemic (restricted) to the area. Three primary vegetation types (Fynbos, Strandveld and Seashore Vegetation) are present in the immediate area, with numerous different plant communities (rocky outcrops, wetlands, dunes, etc) making up these three vegetation types. It is estimated that about 800 – 1000 indigenous plant species occur within a 1km radius of Scarborough, including about 30 which are found only on the south Peninsula. Many are extremely cryptic, or occur in low numbers, and even an observant walker is likely to notice a maximum of only about a third to half this number on any particular day.

Scarborough is firmly nested within the Fynbos biome, located within what is now known as the Core Region of the Greater Cape Floristic Region (GCFR). The GCFR is one of only six Floristic Regions in the world, and is the only one largely confined to a single country (the Succulent Karoo component extends into southern Namibia). It is also by far the smallest floristic region, occupying only 0.2% of the world’s land surface, and supporting about 11500 plant species, over half of all the plant species in South Africa (on 12% of the land area). At least 70% of all the species in the Cape region do not occur elsewhere, and many have very small home ranges (these are known as narrow endemics). Many of the lowland habitats are under pressure from agriculture, urbanisation and alien plants, and thus many of the range restricted species are also under severe threat of extinction, as habitat is reduced to extremely small fragments.   Data from the nationwide plant Red Listing project indicate that 67% of the threatened plant species in the country occur only in the southwestern Cape, and these total over 1800 species! The southwestern Cape is a major national and global conservation priority, and is quite unlike anywhere else in the country in terms of the number of threatened plant species.

 

At a finer scale the Cape Peninsula itself is an international “hotspot” of plant diversity, with about 160 endemic plant species (i.e. species found only in this area). This high figure is a function of various factors, including the fact that the area was isolated from the rest of the Cape Fold Mountains by higher sea levels that covered much of the Cape Flats not too long ago (in geological terms), high topographic diversity, strong rainfall gradients and various soil types.

 

The soils in the mountain area are primarily white, acid sands derived from weathered Peninsula formation sandstones, and they are very infertile, with poor agricultural potential. The coastal sands are more alkaline, and slightly more fertile. Richer shale and granite derived soils do not occur in the area, although there are ferricrete (koffieklip) patches near Redhill.

 

The three main vegetation types in the area are Cape Flats Dune Strandveld, Peninsula Sandstone Fynbos, and Cape Seashore Vegetation.

 

Peninsula Sandstone Fynbos is present on the acid sands all over the Peninsula, and is the vegetation type on the Redhill Plateau behind Scarborough and in most of the Table Mountain National Park (TMNP) south of Scarborough. Cape Flats Dune Strandveld is still widespread on the west coast of the southern Cape Peninsula, from Chapman’s Peak to Cape Point, and is restricted to areas of alkaline (marine) sands. Cape Seashore Vegetation occupies the coastal fringe, and is well represented in the Scarborough area.

 

Cape Flats Dune Strandveld has been classified as an Endangered vegetation type on a national basis, and is severely threatened on the Cape Flats itself, where it is rapidly disappearing. Peninsula Sandstone Fynbos is also technically classified as an Endangered vegetation type, but this is because of the very high number of threatened and localised plant species in the unit, rather than the actual percentage of habitat remaining (the latter being the reason for Cape Flats Dune Strandveld). Some 93% of its total original extent remains, virtually 100% is protected (mostly within the TMNP) and the national conservation target of 30% has been far exceeded. Cape Seashore Vegetation is not regarded as threatened.

 

Four plant Species of Conservation Concern (SCC; previously known as Red Data or Red Listed species) are commonly found within the Scarborough area, including Leucospermum conocarpodendron ssp. viridum (kreupelhout; Listed as Near Threatened), Liparia parva (dwarf mountain dahlia; Vulnerable), Podalyria sericea (Vulnerable) and Serruria villosa (Rare).

Serruria villosa (Valley Spiderhead)

The sweetly scented Serruria villosa (Valley Spiderhead) is found only on the south Peninsula mountains and luckily quite easily found on the mountains above Scarborough

 

Fynbos is a fire driven ecosystem, and is well adapted to regular fires every 8 to 20 years, in contrast to the Strandveld and Seashore Vegetation types, which do not require fire for optimal ecological functioning (and hence generally do not burn, or burnt at lower frequencies). In the long term absence of fire the Fynbos plant community will change to more closely resemble a thicket, with many species becoming locally extinct, and longer lived or resprouting species dominating.   This can be seen within Scarborough, where things like the kreupelhout (pincushion) slowly die out after more than 30 years without fire (their seeds sit underground in ant nests, awaiting fire to stimulate their germination). Fires at the appropriate frequency, and at the appropriate time of year (late dry season) result in a community initially dominated by annuals, geophytes (bulbs) and resprouters, and the slower growing reseeders (like many Protea or Leucadendron species) only become prominent in the third year after the fire, and may not set seed for the first time until four years after the fire, which is why too frequent fires can also lead to local extinction of species. The longer a Fynbos system sits without fire the more fire prone it becomes, with the accumulation of dead wood providing a handy fuel load. This self regulating system eventually tips over into a thicket habitat that can survive without fire, but if reset by fire will then usually follow the normal recovery route, becoming Fynbos again after a few years.

 

Plate 1 - Red Hot Pokers (Kniphofia uvaria)

Red Hot Pokers (Kniphofia uvaria) flower en masse in the Scarborough wetland in the first year after fire, and are then barely noticeable in subsequent years.

 

Nick Helm is a Local Scarborough Resident; botanist and planthunter, based in the Cape Floristic Region, but happy to venture anywhere else that’s biologically interesting. Nick can be contacted by email. Email Nick.