Farmer's Weekly (South Africa)
Reading the veld
The types of grasses or shrubs that grow on any particular piece of veld will give you an idea of what phase of plant succession that veld is in. This will guide you on how to manage it, writes Roelof Bezuidenhout.
Knowing the phase that your farm, camps or sections of camps are in will help you understand the general condition of the veld, its grazing capacity and its realistic stocking rate. It will also help you to plan management strategies for each section.
THE THREE GRASSVELD STAGES
The main phases of succession are the pioneer, subclimax and climax stages, with environmental stability increasing towards the climax stage, and vice versa. When veld reaches the pioneer stage, you might have to implement special measures to kick-start it into the next stage.
The pioneer stage is found on bare and disturbed soils; such areas have low grazing capacity. As the condition of the soil improves with time, the plant cover increases and the pioneer species give way to species better adapted to the improved conditions. As this happens, grazing quality improves.
The climax stage has the highest production capacity of all the stages. However, it is not necessarily the best stage for grazing, and you might have to use good veld management techniques, such as judicious burning, to maintain the vegetation in the optimal grazing condition.
Progressive succession leads to veld improvement while retrogressive succession leads to veld deterioration. Retrogressive succession can result from overgrazing.
Certain plant species are characteristic of the different stages of succession and can therefore be used as indicators of veld condition. For example, in summer rainfall areas, brown stick grass ( Aristida adscensionis) is a pioneer grass species, heart seed grass ( Eragrostis superba) is a subclimax grass species, and rooigras ( Themeda triandra) is a climax grass species. The Karoo also has a list of dwarf shrubs that fall into the different succession stages.
Get to know the various indicator plant species so that you can detect changes in veld condition. If necessary, you can then correct these changes.
VELD CONDITION
Veld condition, as determined from species composition, is used to estimate the grazing capacity of a farm or even a camp. Grazing capacity is the potential of the veld to support livestock and is expressed as the number of cattle, sheep or goats that can be supported by the veld without the grass deteriorating due to over-utilisation or underutilisation. Grazing capacity should be seen as a balance between plant production and animal production.
THE MAIN PHASES OF SUCCESSION IN GRASSVELD ARE THE PIONEER, SUBCLIMAX AND CLIMAX STAGES
The condition of a piece of veld depends on the management practices applied, for example conservative or moderate stocking rates. The aim should be maintain veld condition at an optimal level.
The first step to drawing up a veld management programme is to assess the veld condition in each camp or group of camps. You want there to be enough palatable plants for your animals to graze and convert into meat or fibre.
Keep in mind, though, that the various grass species differ from each other in their grazing value. The species that occur in a particular section of veld will indicate overgrazing or undergrazing. Veld dominated by unpalatable species points to overgrazing.