FYNBOS

The various Fynbos vegetation types comprise most of the area of the Fynbos Biome. Fynbos is characterized by the presence of the following three elements:

1. A restioid component, belonging to the Restionaceae or the Cape Reed Family. Some definitions require a mere 5% cover of restiods in an area to classify it as a Fynbos vegetation type. The Restionaceae have been described as shrubby grasses, and replace grasses on nutrient-poor soils where there is a strong winter component to the annual rainfall. Sedges and many grasses within Fynbos also share the "restioid" characters of reduced or absent leaves and tough, wiry stems.

2. An ericoid or heath component. By far the majority of plant species - and the greatest cover after restioids comprise plants with small, narrow, rolled leaves with thick-walled cells on the upper leaf surface and a channel containing hairs on the lower surface. Although the Heaths (Ericaceae) feature prominently, the Daisy (Asteraceae), Blacktip (Bruniaceae), Pea (Fabaceae), Jujube (Rhamnaceae) and Thyme (Thymelaeaceae) Families also have structurally similar leaves. Many of these plants are wispy and insubstantial, although some form quite dense bushes.

3. A proteoid component. These plants, almost exclusively of the Proteaceae, have broad, isobilateral (both surfaces similar) leaves. They are the dominant overstorey in Fynbos. Although some members occur in ecotones and some occur in Renosterveld, by far the majority are confined to Fynbos.

Fynbos is characterized by the presence of seven endemic or near-endemic plant families: Blacktips (Bruniaceae), Guyalone (Geissolomaceae), Sillyberry (Grubbiaceae), Brickleaf (Penaeaceae), Buttbush (Retziaceae), Dewstick (Roridulaceae) and Candlestick (Stilbaceae). Only the Bruniaceae (75 spp.), Penaeaceae (21 spp.) and Stilbaceae (13 spp.) comprise more than five species. The fifteen largest families comprise 70% of the species in the Fynbos Biome (Table 3).

Over 7 000 plant species occur in the Fynbos vegetation types. Endemicity is very high - over 80% of plant species are confined to the Cape Floral Kingdom and Fynbos Biome. The majority of these, although exact numbers are unknown, are confined to one or more of the various Fynbos vegetation types.

Many species have very narrow distributional ranges. Thus, based on the Proteaceae for which we have the most finely detailed data, some 24 centres of endemism (areas with species sharing similar localized distributional ranges) have been identified.

Table 3. The largest families and genera in the Cape Floral Kingdom. Included are all families with over 200 species (and their largest genus) and those families containing a genus with more than 100 species. (Source: Bond & Goldblatt 1984)

Family	Total species	Endemic species	Largest genus	Species
Daisy: Asteraceae Heath: Ericaceae Vygie: Mesembryanthemaceae Pea: Fabaceae Iris: Iridaceae Protea: Proteaceae Cape Reed: Restionaceae Figwort: Scrophulariaceae Buchu: Rutaceae Bellflower: Campanulaceae Orchid: Orchidaceae Sedges: Cyperaceae Milkwort: Polygalaceae Jujube: Rhamnaceae Storkbill: Geraniaceae Sorrel: Oxalidaceae Rose: Rosaceae	986 722 660 644 612 320 310 310 259 222 206 203 139 136 133 129 114	608 700 507 525 485 306 329 160 242 157 124 124 117 122 67 90 97	Senecio Erica Ruschia Aspalathus Gladiolus Leucadendron Restio Selago Agathosma Lobelia Disa Ficinia Muraltia Phylica Pelargonium Oxalis Cliffortia	113 550 138 245 88 80 85 59 130 42 52 57 106 133 125 129 106

Table 4. Centres of endemism in the Fynbos vegetation types of the Cape Floral Kingdom. (*=not shown; provinces are biogeographical, not political) (Source: Rebelo 1994) Codes - refer to Fig.1 on page 70

Centre of Endemism	Code	Proteaceae species		Extent (km²)	Proportion conserved (%)
		Total	Endemic
Grassy Fynbos
Kouga District	Ko+C	30	2	6658	27
Laterite Fynbos
Bredasdorp District	Br	12	5	615	0
Limestone Fynbos
Bredasdorp District Mossel Bay District	Br Mo	16 19	3 3	1050 1549	25 2
Mountain Fynbos
Kamiesberg Province*	-	2	2	?	0
North-western Province
Cederberg District Great Winterhoek District Piketberg District Bokkeveld Zone Gifberg Zone	Ce Gw Pi Bo Gi	63 103 33 12 24	7 10 2 3 3	2569 2206 494 850 2370	86 73 0 6 0
South-western Province
Peninsula District Riviersonderend District Franshoek District DuToitskloof District HouwHoek District Bredasdorp District Potberg District	Cp Ri Fr Dt H Br Po	38 65 102 90 98 51 33	9 7 3 4 22 2 3	278 912 596 1369 991 650 130	100 80 98 89 65 8 19
Coastal Mountain Province
Koo-Langeberg District Langeberg District Outeniqua District	Ro Ln Ts	58 63 36	3 9 4	722 1853 1619	83 46 96v
South-eastern Province
Swartberg District Witteberg District	Sw+Ks+Ki Wi	57 22	13 2	3475 161	66 0
Sand Plain Fynbos
Sandveld Zone Malmesbury District Peninsula District	Sa Ma Cp	32 34 33	3 4 5	2306 972 300	0 4 0

Whereas there is near unanimity as to the definition of Fynbos as a unit, there are widely divergent opinions on the major vegetation types within Fynbos. This stems from the high species richness and the large number of localized species, which prevents an easy comparison of species lists between centres of endemism. Consequently, the definition of vegetation types based on species composition, the basis for determining types in the other biomes, has never been achieved in Fynbos.

A structural approach, suggested by Campbell in 1985, recognises Proteoid, Ericaceous, Restioid, Asteraceous, Shrubby and Grassy vegetation types. This approach denies a difference in Fynbos types between the mountains and the lowlands of the Biome. However, the different types occur on a scale too fine to map here Ericaceous on the wet, upper south slopes, Asteraceous on the drier northern slopes and the wetter, shale-derived soils, Restioid on the winter water-logged and summer and slopes, and Proteoid on the richer colluvial, sandstone-derived soils. Shrubby Fynbos is ecotonal to forest where rock outcrops, gorges and stream courses protect the vegetation from fires, and Grassy Fynbos predominates where the summer component of the rainfall allows grasses to outcompete the restioids. These basic components are further subdivided into over 60 types based on structural adaptations.

An older classification by Moll & Bossi in 1983, recognized three main types of Fynbos. These are Mountain, Grassy and Lowland Fynbos. The Grassy type corresponds to that of Campbell. However, the Mountain and Lowland dichotomy has never been defined or defended. It has been criticised as merely one of cartographic convenience. Mountain Fynbos was classified into Dry, Mesic and Wet Fynbos, with a fourth type - Arid (for the northern Cederberg and Swartberg) - perhaps required. Grassy Fynbos was categorized as either Mesic (on southern slopes and nearer the coast) or Dry (northern slopes and predominantly inland). Lowland Fynbos was subdivided into three main types based on their edaphic (soil) requirements. Of the three, only the subdivisions of the Lowland Fynbos types correspond to mapable patterns of endemism and are adopted here (the other units were recognized on LANDSAT satellite imagery, but do not correspond to structural vegetation type classes).

Fynbos vegetation types occur predominantly on well leached, infertile soils. The Cape Supergroup sandstones typically produce such soils, but under high rainfall conditions, granites and even shales become sufficiently leached to support Asteraceous Fynbos, replacing Renosterveld. This usually occurs at about 600 to 800 mm annual rainfall, but may be much less on granites, especially at higher altitudes. Below 200 mm Fynbos is replaced by Succulent Karoo, presumably because at such low rainfall, the vegetation does not burn frequently enough.

Fynbos has a low animal biomass, although species richness of birds, mammals, frogs, reptiles and insects is quite high, and most Fynbos Biome endemics occur in Fynbos vegetation types. Although these animals play a major role in pollination and seed dispersal, they appear to play a minor part in influencing vegetation structure and composition. This is partly due to the high carbon to nitrogen ratio, which effectively excludes browsing of all but the youngest leaves.

Fire is a major influence on Fynbos community processes. Fynbos must burn at between 6 and 45 years of age in order to sustain its plant species. Many species store their fruit in fire-safe cones for release after a fire, and ants are enticed to bury fruit where they are safe from rodents and fire. After fire many plant species resprout, but the majority rely on the predictability of fires and only regenerate after the fire from seeds. Without fire, Fynbos becomes senescent and Forest and Thicket elements begin invading.

Because of the low productivity of Fynbos vegetation types, due to the infertile soils, they are little utilized for agriculture. The major use of Fynbos is for recreation, water catchment and exotic plantations. In some areas vegetation harvesting for the cut-flower trade occurs, and wild flower orchards are being established in Fynbos areas. The implications of these for hybridization and gene transfer are poorly understood and are of conservation significance - we need to conserve the genetic material for future cultivar selections rather than lose wild genetic reserves by careless orchard placement. On richer soils where the rainfall is high, Fynbos has been converted to fruit orchards and vineyards. With more modern agricultural techniques (liquid fertilisation, terracing, hydroponics) much marginal land is becoming suitable for agriculture. At present dam building - both for agricultural and urban use - is a threat, albeit a minor one, compared with alien encroachment, urbanization and fires.

Key References:

Moll & Bossi (1983), Moll et al. (1984), Campbell (1985),

Cowling (1992), Cowling & Richardson (1995).

Author:

Tony Rebelo.