CB20200: Veld Types

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Natural veld in South Africa can be divided into the sweet, sour and mixed veld. These veld types differ mainly in the nutrient value and the palatability of the common grasses during the dormant season when the plants are not growing.

Nutrient value – the number of nutrients that a plant contains at a specific stage.

Palatability – the tastiness of food as experienced by animals.

Translocation of nutrients – the movement of nutrients from the plant’s roots to the left base to survive during its growth period.

Climatic factors such as rainfall and temperature play a major role in the environment regarding the adoption of plant species.

High rainfall areas - plant nutrients are leached from the soil, causing soil low in pH and fertility, with the result of a sour veld.

The severe winter with frost is typical of the sour veld area and plants adapted to the frost by translocation the nutrients from the leave-base, back to the roots.

Sweet veld occurs in the lower rainfall areas where only a small amount of nutrients are leached out of the soil during the rainy season. The plants in the sweet veld do not translocation the nutrients to the roots as the temperature is usually higher than in the sour veld areas.

Characteristics of Sweet, Sour And Mixed Veld

Sweet Veld

Occurs mainly in the lower laying frost-free areas
Rainfall usually range from 250 – 500 mm per annum
Most grasses remain palatable throughout the year, provided that the veld is in a good condition.
Is sensitive to overgrazing during the growth season
Recovers quickly after being grazed, provided that growing conditions is optimum.

Sour Veld

Is found at higher altitudes with lower temperatures
Rainfall 625 mm per annum and more
Produce palatable grazing with a fairly high nutritive value during the growth season
Can withstand overgrazing but resulting in lower production
Recovers slower from utilisation than sweet veld

Mixed Veld

The intermediary form between sweet and sour veld
Characteristics similar to that of sweet veld - known as sweet mixed veld
Characteristics similar to that of sour veld - known as sour mixed veld

The different veld types must be managed differently to utilise the veld when it is at its best with the highest nutritive value and palatability

Ecosystems - Biomes

Click here to view a video that explains the Biome ecosystem.

The study of ecosystems is based on the view that all the elements of a life-supporting environment of any size, whether natural or man-made, are parts of an integrated network in which each element interacts directly or indirectly with all others and affects the function of the whole.

All ecosystems are contained within the largest system known as the ecosphere, which includes the entire physical Earth (geo-sphere) and all of its biological components (biosphere).

An ecosystem is a combination of biotic components – living elements and a-biotic - non-living elements which include minerals, climate, soil, water and sunlight.

The abiotic and biotic systems are linked by two major forces:

The flow of energy through the ecosystem; and
Cycling of nutrients within the ecosystem.

The fundamental source of energy in almost all ecosystems is energy captured from the sun. The ecosystem’s autotrophic (self-sustaining) organisms (found in green vegetation) are capable of photosynthesis as they use sunlight energy to convert carbon dioxide and water into simple, energy-rich carbohydrates.

The autotrophic organisms use the energy, stored within the simple carbohydrates, to produce the more complex organic compounds, such as proteins, lipids and starches that maintain the organisms' life processes. The autotrophic segment of the ecosystem is commonly referred to as the producer level.

The organic matter generated by autotrophic organisms, directly or indirectly, sustains heterotrophic organisms. Heterotrophic organisms are the consumers of the ecosystem; they cannot make their own food. They use, rearrange and ultimately decompose these complex organic materials built up by the autotrophic organisms. All animals, fungi, most bacteria and many other microorganisms are heterotrophic organisms.

As a combination, autotrophy and heterotrophy will form various strophic (feeding) levels in the ecosystem:

The producer level – a combination of autotrophic organisms which manufactures their own food;

The primary-consumer level – a combination of organisms that feed on producers;

The secondary-consumer level – a combination of those organisms that feed on primary consumers.

The movement of organic matter and energy from the producer level through various consumer levels makes up a food chain.

For example: - a typical food chain in grassland might be grass (producer) → mice (primary consumers) → snakes (secondary consumers) → hawk (tertiary consumers). Actually, in many cases, the food chains of the ecosystem overlap as well as interconnect to form what ecologists call a food web. The final link in all food chains is made up of heterotrophy decomposers that break down dead organisms and organic waste.

A food chain in which the primary consumer feeds on living plants is called a grazing pathway. If the primary consumer feeds on dead plant matter, it is known as a detritus pathway. Both pathways are important in accounting for the energy budget of the ecosystem.

As energy moves through the ecosystem, much of it is lost at each tropic level. For example, only about 10 percent of the energy stored in the grass is incorporated into the body of a mouse that eats the grass. The remaining 90 percent is stored in compounds that cannot be broken down by the mouse or are lost as heat during the mouse's metabolic processes. Energy losses of similar magnitudes occur at every level of the food chain; consequently, few food chains extend beyond five members (from producer through to decomposer) because the energy available at higher atrophic levels is too low to support further consumers.

The flow of energy through the ecosystem drives the movement of nutrients within the ecosystem. Nutrients are chemical elements and compounds necessary to living organisms. Unlike energy, which is continuously lost from the ecosystem, nutrients are cycled through the ecosystem, oscillating between the biotic and abiotic components in what are called biogeochemical cycles. Major biogeochemical cycles include the water cycle, carbon cycle, oxygen cycle, nitrogen cycle, phosphorus cycle, sulphur cycle and calcium cycle. Decomposers play a key role in many of these cycles as nutrients are returned to the soil, water or air where the biotic elements of the ecosystem can again use them.

An ecosystem is a system of living organisms that lives together and influences each other in different complementary ways, symbiotic or parasitic.

The ecosystem is divided into different biomes. A biome is formed by the influence of climate on living and non-living organisms of a specific region and by the adaptation of the vegetation (plants) to these climatic conditions

Biomes can be defined as the largest land community which is characterised by the uniformity of the general climax vegetation. In the grassland biome, grasses are characteristic but the dominant species may vary from area to area. A biome does not only consist of vegetation but also includes living organisms that find a suitable habitat within. In South Africa, six different biomes are recognised.