Glossary


Acocks' Veld types: A well-known delimitation of vegetation types in South Africa carried out by John Acocks in 1953, in which he designated "veld types" based on areas of similar agricultural land-use potential.

Afromontane (region): The area of high altitudes on the mountains of Africa. The Fynbos Biome is considered by some to be Afromontane in that the Afromontane vegetation tends to be highest in the tropics and towards the poles.

Aeolian (soil): Wind-borne. Moved by wind rather than water or by decomposition of local rock. Most aeolian sand is of marine origin, although some rivers may provide sand for wind dispersal.

Andesite lava (geology): An igneous rock, comprised mostly of the mineral feldspar. It forms an erosion resistant rock with a dark green colour, and is best developed in the Ventersdorp Supergroup lavas.

Apedal (soil): A soil having no visible internal structure.

Berg Wind (climate): A katabatic (downslope and generally offshore) wind of especially the west and south coast of South Africa, which is both hot and dry and therefore conducive to fire spread.

Biodiversity: The sum of all species of animals, plants, fungi and micro-organisms. The total biodiversity of a region is generally unknown, and is commonly expressed simply as the number of animal and/or plant species known to occur in the region.

Biome (region): A broad ecological unit representing major life zones of large natural areas. In South Africa these are defined mainly by vegetation structure and climate.

Brokenveld (topography): A region characterized by rugged topography, preventing easy thoroughfare. The granitic landscapes of the Succulent Karoo are good examples.

C3 grass (plant growth form): A grass having the typical photosynthetic system, in which photosynthesis takes place in all cells of the leaf. The name derives from the initial fixing of CO2 is three-carbon chain compounds. This form dominates temperate regions, but is replaced by C4 grasses in the tropics.

C4 grass (plant growth form): A grass having an alternative photosynthetic system to C3, in which the initial fixing of CO2 is via a four-carbon chain compound. These species have the photosynthesizing cells concentrated around the vascular bundles, whereas the cells elsewhere in the leaf specialize in absorbing CO2 from the atmosphere. At higher light intensifies and higher temperatures, C4 photosynthesis is more efficient, hence its prominence amongst grasses (and other plant species) in the warmer, summer-rainfall regions.

Calcrete (mineral): A mineral formed in the soil profile at the water-table when calcium carbonates accumulate and cement together to form a hard, rock band.

Calcareous (soil): A soil or rock containing calcium carbonate, or related minerals, so that it effervesces (bubbles off CO 2) when treated with acid (cf. dolomite). Usually formed from shells or chemical precipitation, these soils and rocks tend to be coastal in occurrence.

Climax (vegetation): That vegetation type or plant community structure which occurs at the end of the seral cycle. The climax communities may not be the final end point of the succession: frequent, or even rare events, such as fire, frost, harvesting, or hurricanes, may hold the communities in a stable subclimax indefinitely.

Conglomerate (geology): A rock type consisting of rounded pebbles or small rocks cemented with sands silts or clays into a solid rock.

Craton: An old portion of the earth's crust which is relatively stable. Most of the rock tends to be granitic in character. The two cratons in South Africa are the Kaapvaal Craton and the Richtersveld Craton. The Karoo Sequence and Cape Fold Belt are the major sequences which do not cover cratons.

Cupressoid (plant growth form): Plants with small, awlshaped leaves which clasp the stem, resembling those of a cypress.

Dolerite (geology): An igneous rock with fine grains, consisting of equal quantities of the minerals feldspar and pyroxene. During the Jurassic Period, enormous quantities of dolerite were injected into the Karoo Sequence deposits as vertical dykes and horizontal sills. Because of its resistance to erosion, dolerite dykes and sills have shaped many landscapes, especially the eastern Karoo.

Dolomite (geology): A carbonate of calcium or magnesium (cf. calcrete) which only effervesces with dilute acid if powdered or heated. The Bushveld Complex comprises much dolomite, formed by algal deposition of calcium carbonate. Dolomite dissolves giving rise to sinkholes (as in Gauteng), but also stores water, giving rise to the "eyes" in North-West Province.

Duplex (soil): A soil type with a porous topsoil on top of a non-porous layer of soil, usually sand over clay. This does not apply to hardpan layers which form within a soil type due to cementing by iron oxides (ferricrete, laterite), silica (silcrete) or lime (calcrete).

Dystrophic (soil): A markedly leached soil, which has lost most of its calcium, magnesium, potassium and phosphorus, and is therefore generally unsuitable for agriculture.

Ecotone (region): A zone in which two or more vegetation types or ecosystems overlap. These overlaps may be rich in species from both systems, or may occur as species-poor fringes.

Endemic (region): A plant or animal species, or a vegetation type, which is naturally restricted to a particular, defined region. This is not the same as the medical definition, which is "occurring naturally in a region" - it is thus often confused with indigenous.

Epiphyte (plant growth form): Plants which grow on plants, but which are not parasitic and use the other plants only as a perch for obtaining better light or nutrients.

Ferricrete (mineral): A mineral formed in the soil profile at the water-table when iron-oxides accumulate and cement together to form a gravelly or nodule-rich band. This may become impervious to water (cf. duplex). When exposed it is popularly used for gravel roads. Also known as hardpan, ironpan, laterite, ouklip or ngubane.

Floristic: Relating to plants or their distribution.

Forb (plant growth form): A plant without secondary thickening (i.e. non-woody), usually living for only one or two seasons.

Gabbro (geology): A dark, coarse-grained rock, consisting of the minerals calcium, feldspar and crystals of the pyroxene group. The Bushveld Complex is largely norite, a type of gabbro, and contains the majority of South Africa's chromium, platinum and magnetite ores.

Geophyte (plant growth form): A plant which has its permanent parts in the ground, and in which the aerial parts die back annually. The flowers may be produced before, with or after the leaves. Important groups of geophytes include the ]rises (with corms), the various Lily families (with bulbs and rhizomes underground stems), and many ferns (with rhizomes).

Geoxylophyte (plant growth form): A plant characterized by having annual or short-lived woody shoots which sprout from a massive or extensive, perennial, underground stem.

Gleying (soil): Intense chemical reduction in prolonged waterlogged soils. Generally grey (no iron) or blue-green (iron present) in colour.

Granophyre (geology): A type of granitic rock.

Habitat (region): The home of any animal or plant species. Generally those features of an area inhabited by animal or plant which are essential to its survival.

Halophytic (plant growth form): A plant which grows in salty environments, or which can tolerate high levels of salts.

Heuweltjie (land form): A raised mound, 2-5+ m in diameter, which occurs in the western Northern Cape and Western Cape Provinces. These are thought to have been formed by termites. With their higher calcium levels and more clayey soils, they often support distinctive plant communities. This is especially prominent in Renosterveld vegetation types (Fynbos Biome) which may have Thicket on the heuweltjies.

Hot spot (region): An area containing a high number of species, usually coupled with a high proportion of endemic species. Such areas are conservation priorities, as they have high biodiversity values.

Igneous (geology): A rock which forms by the deposition of magma or lava, usually as deep intrusions into rock layers but occasionally on the surface as volcanism. Granite is the commonest intrusive igneous rock. The Basalt capping on the Drakensberg is formed from a series of surface lava flows totalling 1.5 km thick. The other major rock types are sedimentary (deposited by wind and water) and metamorphic (a preexisting rock which has been transformed by high pressure and temperatures or by chemicals).

Indigenous (region): Occurring naturally in a defined area. (cf. endemic). it is important to note that the area must be specified. Thus the Baobab Adansonia digitata is indigenous to South Africa, but it is not indigenous to Natal. The Marsh Rose Orothamnus zeyheri is indigenous and endemic to Western Cape and South Africa, but not to Eastern Cape.

Laterite (geology): A hardpan (cf. ferricrete, calcrete) formed by the precipitation of iron oxides in the fluctuation zone of the watertable.

Liana (plant growth form): Vines or plants with long dangling stems, with roots in the ground and leafy parts in the canopy, usually supported by the branches of trees.

Lithocutanic B-horizon (soil): Soils which have weathered rock beneath the A-horizon (the uppermost layer).

Lithosol (soil): A shallow soil, comprising mostly bedrock or rock fragments with some weathered material. Generally these soils are young and show little development of profiles.

Mesa (landform): A flat-topped hillock, formed by a hard sandstone sheet or dolerite sill capping which protects the underlying softer rock from erosion. Mesas and the smaller buttes (which have eroded to a mere pinnacle) are typical of many Karoo landscapes.

Mesic (region): An intermediate state between dry and wet in either climate or soil water characteristics. Montmorillonite (soil): Clays with a 2:1 lattice arrangement, found mainly in fertile soils. They store water extremely well.

Muti: Plants (or animals or minerals), or parts of plants, used in traditional African medicines.

Pediment (soil): The flat area at the footslope of a mountain or hill.

Physiognomy: The structure and life form characteristics of a particular plant community or vegetation type.

Phytochorion, -a (region): A defined vegetation unit, based on Braun-Blanquet methodologies, and defined solely by the presence or absence of certain plant or combinations of plant species.

Podzol (soil): A soil in which the minerals (especially iron), clay and organic matter, have been leached out, giving rise to a white middle layer (an E horizon). This typically occurs in soils derived from quartzitic sands under acidic conditions. It is the characteristic soil type under heath, Fynbos and coniferous vegetation.

Regic (soil): A blanket of soil, usually sand, which has been deposited over another soil or rock, and which has not yet had time to develop profiles or layers.

Rhyolite (geology): A dull, pink, streaky, igneous rock formed from minute glassy crystals of volcanic dust. In South Africa it is found only in the Lebombo Mountains, and is used for roads, concrete and insulation.

Sclerophyllous: Plants characterized by hard, woody leaves, which snap rather than bend, and high carbon to nitrogen ratios which make them unpalatable to browsers. Typical of plants found on nutrient-poor soils, especially Fynbos.

Scrub (vegetation): Thicket vegetation dominated by shrubs, generally dense and almost impenetrable.

Seral (succession): A stage in the natural progression of colonization by plants from bare soil to climax vegetation. Even within climax vegetation tree fails and other events result in a progressive series of stages.

Shrub (plant growth form): A plant intermediate between a tree and a forb, but with the characteristic secondary thickening (woodiness) of the former. Shrubs are typically well-branched and the term is often restricted to plants less than 2 or 3 m tall.

Shrub(veld)/land (region): A vegetation type in which the plants do not reach the size of trees -generally less than 3m tall.

Solonetzic (soil): A soil with a thin porous topsoil, with a columnar, salty or sodium-rich subsoil.

Sour(veld) (region): A vegetation type in which the grasses are largely unpalatable outside of the growing season. This is usually due to a very low nitrogen to carbon ratio which makes then indigestible to livestock. Sourveld tends to occur on soils which are infertile and acidic.

Stratum, -a (geology, soil, vegetation): A horizontal layer or set of layers of either rock or soil, or plants within a community.

Succession: A series of stages (cf. sera) in which different plants and animals colonize an area following some kind of disturbance. The final stage of the succession is called the "climax", but various disturbances may prevent the vegetation from attaining its potential climax. The Fynbos, Grassland and Savanna Biomes have a "fire-climax", in which fire prevents the succession from progressing to forest, in suitable habitats.

Succulent (veld) (region): A vegetation type dominated by plants which store water in their stems and/or leaves.

Sustainable: A practice which can be carried out indefinitely, without adversely affecting the environment, or interfering with the practice. This implies that the practice (e.g. harvesting, grazing, farming) is in balance with the energy,; water and mineral cycles of the region, or else is able to be maintained in equilibrium with judicious augmentation of fertiliser or organic material. Excluded are practices which mine resources (e.g. mining, extracting non-replenishable water), which lead to irreversible degradation (e.g. soil erosion, water pollution by fertilizers, salt accumulation) or which compromise natural processes (e.g. canalization, wetland destruction, seed bank depletion). Sweet(veld) (region): A vegetation type which contains grasses which remain palatable for most of the year. This usually occurs on richer, more alkaline soils.

Terracette: A small terrace.

Thorn Bushveld (region): A vegetation type dominated by trees with spiny thorns, mainly Acacia species. Tongoland-Pondoland (region): The coastal region from southern Mozambique southwards through KwaZulu-Natal to the eastern parts of the Eastern Cape. Also known as the Maputaland-Pondoland Region.

Tree (plant growth form): A vaguely defined growth form ("everyone knows what a tree is"), typically considered to comprise plants taller than 3 m (occasionally 2 or 5 m) and to have a single basal trunk.

Tufa (soil): A porous, calcareous rock, often found around mineral springs.

Vegetation type: A structurally and floristically defined unit of plant communities, which share similar climatic, geological, and soil requirements, have similar ecosystem processes, and thus have similar management and conservation requirements, as well as potential uses.

Vertic (soil): A soil with a blocky structure, which shrinks and swells markedly depending on wetness, due to a high clay content. These soils tend to be porous and to have a black or dark colour.