Ecological Units within a Veld Type

Sub-division of veld into different homogeneous veld units is an important part of effective farm and veld management

 

Introduction to Variety of Ecological Units

Within any veld, there are different vegetation and ecological units

 

In the previous volume, it was pointed out that many different factors can influence the vegetation. It is therefore obvious that in every country and even within the boundaries of a farm we will find vegetation or veld that differs greatly. The following scheme gives a broad outline of the separate subdivisions as used for botanical purposes:

• Plant formation or floral region
• Veld type
• Sub-veld type
• Association
• Community
• Plant species

A plant formation is the biggest vegetation classification and consists of vegetation that resembles each other in a broad sense, for example, forest, grass veld, macchia or desert. A veld type can be described as a unit of vegetation with about the same farming potential or with the same physiognomy (appearance). A sub-veld type is a further subdivision of a veld type based on plant uniformity, for example, the Arid karoo is further subdivided into sub-types Blomkoolgannaveld and Driedoringveld.

For farm planning, the veld is divided in a slightly different way. The following scheme and the figure on The subdivision of an area into its natural components indicate this type of division.

• Plant formation
• Veld type
• Sub-veld type
• Topographic complex
• Main vegetation type
• Vegetation type
• Sub-vegetation type
• Plant species

The topographic complex has mainly to do with surface characteristics which occur within veld types and are of particular importance in farming practices. A topographic complex can be divided into different main vegetation types according to their relative topographic position.

The subdivision of main vegetation types into vegetation types is based on the relative uniformity of characteristics such as soil type, plant cover and steepness of slopes. The climate is the most important factor that determines a veld type, but as the division becomes smaller, as in the case of vegetation types, other factors such as soil and physiographic factors become more important. The vegetation type represents the smallest practical unit of subdivision concerning farm planning. If a main vegetation type is too small to make a subdivision worthwhile, it can be regarded as a vegetation type.

Sometimes when different communities of limited extent can be recognised, it is termed sub-vegetation types. In practice, they are not separated unless they are regarded as particularly valuable to make separate fencing worthwhile. A sound general knowledge of the most important plant species will help to recognise the differences in a topographic complex.

 

The subdivision of an area into its natural components.

 

The most important general climatic and veld differences within a topographic complex can be summarised as follows:

 

A. Mountains

Different vegetation can be found across the different topography of mountains.

 

Plateau veld:

The soils are moderately deep and stable. Temperatures are usually a bit lower, rainfall is a bit higher, and mist may occur, evaporation is slightly lower and moisture conditions are therefore more favourable in comparison with low-lying areas. As a result of the more favourable moisture conditions, there is a tendency towards grassveld development. On the other hand, the altitude and wind make the climate more unstable which can be detrimental for grassveld compared to lower-lying areas. In high-rainfall areas, the veld is often sour and unpalatable as a result of the leached soils and the low temperatures.

Slopes:

Vegetation on slopes is limited and is largely affected by the depth of the soil and the rate of water infiltration. 

 

The soils are usually shallow and unstable depending on the steepness of the slope and the parent material. The soils are not clayey and have a high infiltration rate, but the water-holding capacity of the soils is sometimes restricted by the shallowness of these soils. On the other hand, soils on slopes are usually covered with large stones or boulders which increases the effectivity of the rain. If 50% of the soil surface consists of stones, 10 mm of rain will have double the wetting effect compared to soil without stones. Furthermore, these stones help to combat evaporation, runoff and erosion, so that moisture conditions on these slopes are above average. Therefore, there is also a strong tendency towards grass and large shrubs in karoo areas. The vegetation differs from sparse cover on steep shale slopes to fairly dense cover on moderate doleritic slopes. With the exception of slopes high above sea level, the vegetation is fairly palatable.

There are marked differences in the vegetation of the different aspects. These differences are mainly due to the inclination of the sun’s rays and the prevailing winds. Western slopes are drier than eastern slopes mainly because they face the dry western winds and the afternoon sun. In dry areas such as the Karoo, southern and northern aspects are about equally palatable, but southern aspects produce more feed. In high rainfall areas southern slopes show a strong tendency towards forest development and become poor grazing.

Kloof (ravine cleft):

Ravine clefts are sheltered areas where different vegetation can be found.

 

The characteristics of kloofs are the same as for slopes but the vegetation may differ markedly because kloofs are usually more sheltered against cold winds. In some exceptions, kloofs act as drainage channels for cold air. Each kloof has automatically two aspects which usually differ.

Hills:

The characteristics of hills are about the same as that of moderate slopes. The soils are usually sandy, moderately deep and fairly stable. The many stones on the soil surface help to combat soil erosion and make the veld fairly resistant to overgrazing. As a result of the differences in aspects and steepness of slopes, hills usually have very mixed vegetation of fairly good quality. As a result of the above-average moisture conditions, there is a strong tendency towards grassveld in hills, especially doleritic hills.

Apron veld:

Apron veld is a transitional stage from mountain veld to plains. The soils are relatively deep and sandy with clay underlayers and are usually a good example of transported soils. The moisture conditions are slightly drier than slopes and hills, but better than those of plains. The soils are fairly stable but vulnerable to erosion when overgrazed. In the Karoo, the vegetation of the apron veld ranges from predominantly grassveld to predominantly Karoo bushveld, depending on the moisture conditions. Apron veld is of moderate quality and palatability.

Plains (flats):

Plains are large open ‘flats’ of land.

 

Plains are usually divided into two vegetation types, namely dry plains and ordinary plains. This division is mainly based on soil type and depth, which is very closely related to moisture conditions in the soil. It is often very difficult to make this division.

The following can be regarded as general characteristics of plains. The soils are generally relatively shallow and clayey. The soils are generally not stony, but in the Karoo, the shallow soils usually lie on top of a gravel layer. There is usually an accumulation of mineral salts which precipitate in the lower soil layers to form hard lime pans. Where there is a considerable accumulation of salts, plains are often called brakveld or saline veld. The vegetation of Brakveld consists mainly of karoo bushes which are very palatable and nutritious. Brakveld can also, depending on the local conditions, be classified as ‘leegteveld’.

As a result of the flat nature of plains, the soil is relatively stable concerning water erosion, but very vulnerable to wind erosion. There is little natural protection and shelter for plains so big temperature variations also occur.

Due to the exposure to the direct rays of the sun and the dry winds, the evaporation on plains is relatively high. This, together with the generally shallow soils, leads to under-average moisture conditions and a resulting sparse cover. The vegetation consists of a mixture of karoobushes and low-producing grass species, for example, stickgrass and kneegrass. The karoo bushes are generally palatable and nutritious, but the production of plains is low.

The most important differences between ordinary plains and dry plains are caused by the soil and are reflected in the vegetation. They can be summarised as follows. In dry plains, the soils are shallow, moisture conditions are poor and the vegetation consists mainly of a good karoobush component with annual and inferior perennial grasses. In ordinary plains, the soils are shallow to moderately deep, moisture conditions are a little better than for dry plains, but still under the average and the vegetation consists of a good karoobush component with a moderate stand of tough perennial grasses, for example, fine seed grass and blue seed grass.

 

B. Leegteveld

Leegteveld represents the most valuable main vegetation type on a farm. In general, leegteveld can be described as veld which received an additional moisture supply apart from the natural rainfall. The nature and amount of this additional moisture determine mainly in which vegetation type the veld will be classified. The classification is therefore again based on moisture conditions in the soil.

Brakleegtes:

Brakleegtes represent the driest type of leegteveld. The soils are usually deep, loamy to clayey and usually contain high concentrations of mineral salts. It is periodically flooded by runoff water from higher areas, but not regularly. The vegetation consists mainly of deep-rooted shrubs which are fairly saline-resistant. The Gannas are typical examples of such shrubs. On the more sandy and wetter patches, grasses can make up a considerable part of the vegetation. The vegetation is very palatable and with a high nutritive value (1975-04-22).

The soils are fairly resistant to water and wind erosion if the vegetation is maintained. The vegetation is fairly resistant to overgrazing, but if it is overgrazed, brackish bare patches usually develop. In these patches, the water absorption rate of the soil becomes very low and wind erosion becomes an important factor. It is extremely difficult to get vegetation back on these bare patches. Furthermore, the spreading of dry gullies from the main channel must be watched very carefully. These dry gullies are difficult to control and act as draining channels which drain the surrounding soil.

Moist ‘vleis’ (swamp or wetland):

Wetlands are valuable areas of land rich in plant diversity and an important area which needs to be protected.

 

Moist vleis (singular in Afrikaans: vlei) are flooded regularly by natural runoff water. The soils are not so very saline or brackish because much of the mineral salts have been leached out by the regular flooding. The soils are deep and loamy but often consist of several layers of clay, silt and sand, deposited by water over the years. The moisture conditions are usually very good and the vegetation consists of a dense perennial grass cover and the shrubs usually found on bralettes.

In some moist vleis, the water table can be as shallow as 7 to 10 m, which can be reached by many plants. The veld has a high production and is also palatable and with a high nutritive value.

When this veld is mismanaged it becomes very susceptible to erosion and can easily be drained by channels and gullies to such an extent that the grass cover is lost. Moist vleis are extremely valuable as a natural drought reserve and with proper management, they can give a grazing capacity of more than twice that of natural veld.

Channels:

Channels usually cause the biggest problems because they tend to drain the surrounding soil and it is difficult to prevent them from extending. With careful management and the aid of mechanical works, it is usually possible to establish plants like ‘fluitjiesriet’ in the channel. The plants will catch sediment which will turn the dry channel into a wet channel which is a much better proposition.

 

C. Summary

The various vegetation types mentioned in this chapter differ concerning the nature of the vegetation, palatability and accessibility. It is therefore quite obvious that within several vegetation types, some will be grazed more than others. To eliminate these dangers of overgrazing on the most palatable veld, it is important and necessary that the different vegetation types should be fenced off as far as practically possible.

 

Introduction to Subdivision of Veld Types

The farmer and an extension officer need to physically plan out the layout and camps on a farm.

 

Before veld management can be put into practice, it is necessary to do a physical plan of the farming unit and to carry it out. The physical planning is usually done by the farmer in consultation with the extension officer and the planning is then carried out step by step by the farmer. For the simplest form of veld management, an average stock farmer must have about six to eight camps.

 

Subdivision of Veld into Camps (see topographic complex)

An example of a farm where camps have been camped off based on different vegetation types. (Source: On Pasture)

 

The natural veld is heterogeneous and there are usually many different vegetation types on a single farm. The first phase is to separate the different veld units, based on topographic and other differences, from each other. At this stage, the topography is the main basis for subdivision and in this way, mountain veld, flats or plains and ‘leegte’ veld are separated from each other. The main vegetation types or geographical types are therefore separated from each other. These are usually the vegetation types that differ the most from each other.

The second phase is the further subdivision of these main vegetation types based on uniformity concerning the following characteristics:

• Topography.
• Number and size of camps.
• Advantages and disadvantages of more and smaller camps.
• Provision of water.
• The shape of camps.
• Shelter and shade.

We will now discuss these aspects in more detail.

 

Topography

Topographic map of South Africa indicating areas of raised topography. Relief map of South Africa – 1967 Polish Army Topography Service Map.
(Source: MapPorn)

 

The aspect of the slope: north, south, east and west.

The steepness of the slope: none, moderately steep, very steep.

Vegetation:

• Dominant component: mainly grass, sweet grassveld, sour grassveld, and so forth, mainly karoo bushes, mainly shrubs or mixed.
• Botanical composition: good – mainly desirable plant species; fair – a mixture of desirable and undesirable plant species; poor – mainly undesirable plant species.
• Palatability: Sweet, sour or mixed – palatable, unpalatable, or mixed.

Soil:

• Soil type: sandy, clayey, stony and so forth (form and series)
• Soil depth: deep, moderately deep, or shallow (phase)
• Erosion condition: badly eroded, moderately eroded, or no erosion.

During this second phase, careful judgment and good background knowledge can be a valuable aid. Usually, the badly eroded areas are fenced off first, and placed under a special treatment, while the erosion is also combatted by mechanical means. Similarly, parts of the veld which contain many poisonous plants or veld which is in a very poor condition can also be fenced off separately. In the high rainfall areas, those parts of the veld that can be used for haymaking are often fenced off separately before any further subdivisions are made.

Although a large number of factors are kept in mind, the subdivision during phase two is mainly based on vegetation characteristics. The reason for this is that changes in the topography and soil usually result in a change or difference in the vegetation. In this way, for example, sweet grass veld is separated from sour grass veld, karoo bush veld from grass veld, climax veld from pioneer veld, and north slopes from south slopes. The idea is to get each camp as uniform as possible concerning the mentioned characteristics. When differences in the veld occur but the veld units are too small to justify separate camps, grouping of different vegetation types can take place, but then the following very important principle must be applied: rather camp a small area of unpalatable or sour veld with a large area of palatable or sweet veld, than the other way found. This will prevent the destruction of small areas of good veld by selective grazing (area selection) when they are camped into poorer veld. The same principle is applied when it is not possible to put the fence precisely on the boundary of two vegetation types because of topographical problems or problems with the provision of water. Often, for example, a piece of apron veld fits better into flats than into mountain veld. It is permissible to group apron veld with flats although apron veld is generally grouped under the main vegetation type: mountain veld.

Where veld is in a very bad condition, soil surveys can be a useful aid in farm planning, because it indicates the potential vegetation. Soil surveys are of great importance in arable areas when it comes to the planning of lands and grazing (veld). The fences erected under phases one and two are known as the primary fences and are subsidised by the government if they comply with certain basic specifications. The primary fences are usually enough to fulfil the requirements of a normal farmer.

Certain camps may still, however, be exceptionally large. Further subdivision can then still take place but at this stage, the differences in the veld usually play a less important role, because the biggest differences have by then been eliminated. Factors like convenience, easier stock management, the shape of the camp, economic considerations, availability of water, and so forth, are then usually the determining factors. These fences are called secondary fences and are not necessarily subsidised by the government.

At this stage it is necessary to refer shortly to the reasons for the subdivision of veld and why attempts are made to separate vegetation types from each other. Vegetation types are separated from each other for the following reasons:

• To make better provision for the requirements of each vegetation type concerning rest, grazing and so forth.
• To combat selective grazing (area selection).
• To get better utilisation.
• To combat soil erosion.

The fact that this automatically leads to more camps, provides the following advantages:

• Better provisions can be made for reserve veld for times of drought.
• Stock management is facilitated.

 

The Number and Size of Camps

 Farm D different camps: a) Planned farm with 19 camps subdivided according to veld types; b) Group A camps; c) Group B camps; d) Group C camps.

 

The number and size of camps will depend on many factors. The most important factors include the following:

The type of veld, the topography of the area, and the number and size of the different vegetation types. The more vegetation types there are and the smaller they are, the more and smaller the camps will tend to be. These conditions are often found in mountainous areas. The higher the rainfalls, the smaller the camps, because the farming pattern will be more intensive. The grazing capacity expressed as ha or SSU multiplied by 100 can indicate an average camp size for a conventional slow rotational system.

Type of farming system and the type of production system:

The size of the flocks will determine to a great extent the size of the camps. Stud farmers usually have more flocks and therefore usually need more camps than ordinary stock farmers. There are also differences concerning the size and number of camps needed for cattle farming, sheep farming, karakul farming, and so forth

The size of the farming unit:

The bigger the farming unit the bigger the camps will normally be.

The availability of water for stock:

A shortage of water for animals often prevents excessive subdivision of veld. It is impossible to state the optimal number of camps and the optimal camp size for each region or each farm. For the Karoo region, six camps per flock are regarded as the absolute minimum to fulfil the requirements of an ordinary farmer and a simple conventional veld management system. The Government however subsidises up to as many as 25 camps per farm and even more under special circumstances. With the planning of his farm and the analysis of his production system the farmer himself will have to decide on the number and size of the camps. Knowledge of the advantages of more camps will help him to make the necessary decisions.

 

Advantages and Disadvantages of More and Smaller Camps

Dividing the farm into smaller camps has advantages and disadvantages.

 

It is often difficult to decide if it is justified to make more and smaller camps, therefore, the advantages and disadvantages of more and smaller camps will be briefly discussed.

Advantages:

• Shorter grazing periods can be applied which will decrease the detrimental effects of grazing and also result in faster recovery of the veld and a better utilisation of the rainfall.
• Longer rest periods for the production of seeds, establishment of seedlings and veld improvement are possible.
• Better control of selective grazing can be obtained.
• A bigger percentage of the veld can be rested at any moment.
• Greater flexibility can be obtained by adapting the management to circumstances.
• Preferential treatment or any other special treatment can more easily be applied to certain flocks or camps. Camps in very poor condition can, for example, receive an extra rest period or another special treatment.
• The stability of the farming system can be increased because more reserve veld can be kept during droughts, and so forth.
• Stock inspection and stock management can be improved and facilitated.

Disadvantages:

The only real disadvantage is the higher capital investment in fences and the provision of water. The figure on Minimal capital investment concerning camp size indicates how the capital investment increases as the camps become smaller.

 
Minimal capital investment concerning camp size.

 

The increased capital investment must be seen as a very long-term investment and must not be considered in terms of the immediate benefits, but in terms of the long-term advantages of the future. Economical considerations are especially important when it comes to secondary fences.

The maintenance and management of more camps require more attention and place higher demands on the management and organisation abilities of the farmer. Mismanagement can lead to faster veld deterioration although veld deterioration can take place with any system and any number of camps.

 

Provision of Water

Windmills and boreholes are valuable resources to have on a farm for the provision of water.

 

The provision of water is usually one of the big problems in extensive arid areas.

The arrival of plastic pipes has made the provision of water for stock much easier. The number of watering points per camp depends on many factors such as the size of the camp and the accessibility of the area. The following general minimum requirements can however be laid down.

• There must be at least one proper drinking point per camp, but preferably more than one, especially if the camp is fairly big.
• The drinking points must be placed as centrally as possible.
• Drinking places must be distributed in such a way that they are not more than 1.5 km from the most remote corners of the camp. This distance decreases in the case of mountainous areas and high-producing animals.
• If cattle and sheep are run together there must be at least two drinking points per camp.
• The water must be of good quality.

 
Clean drinking water is vital for all livestock on a farm.

 

It is interesting to note that cattle need 25 to 50 litres of water per day while sheep need 1.5 to 10 litres. Sheep and goats can graze further from the water and can stay a bit longer without water than cattle. It is worthwhile to see that camps are properly supplied with water because if unnecessary walking of animals can be cut out, the saved energy can be used for production. The water needs of animals change a lot if the nature of the forage and weather conditions change.

 

Shape of Camps

The shape of the camp affects the utilisation of the veld and vegetation.

 

Long and narrow camps must be avoided as far as possible. It frequently causes overgrazing near the water points and undergrazing in the remote corners of the camp. Long narrow camps also lead to unnecessary trampling and wasting of energy because the animals must walk long distances. Long and narrow camps also increase the capital investment per hectare in fences and water provision in relation to more square camps. Camps must therefore be kept as near a square or rectangular form and as compact as possible. Physical planning is a gradual process and therefore the further sub-division of a camp must always be kept in mind when a new fence is planned.

 

Shelter and Shade

Shade within a camp is crucial for the well-being of livestock.

 

The provision of shelter against adverse conditions and shade during summer is often omitted. Exposure of animals to adverse climatic conditions changes their grazing habits and decreases their forage intake. Provision of shelter and shade normally leads to an increase in production; in one specific experiment, the increase was as much as 11%. Normally the planting of trees for windbreaks and shade is recommended.

Other structures can also be put up. The provision of natural shelters in camps such as cliffs, ridges, ravines, and so forth, must also be considered in the planning and erecting of new fences, especially secondary fences.