A grassland garden contains the grasses associated with our Grassland Biome as well as the perennials and geophytes that also occur amongst the grasses. One can consider this as a locally flavoured “meadow” that the British are very fond of. Although a low maintenance garden, it is certainly not maintenance free.
But let us first look how the natural grasslands in South Africa “maintained” itself in the not so distant past.
Large herds of antelope would migrate across the grassland plains and mow the grasses down in a very short period due to sheer numbers. Their hooves disturbed the soil and in many cases left little pockets where rainwater can accumulate. When they move on, the grasses re-sprout and set seed before it dies back in winter.
In early spring, lightning would cause veld fires. The grasses are burnt to the ground as well as all the other perennials amongst the grasses. Where tree saplings are not protected (for instance amongst rocky outcrops) they also perish.
But how do the majority of the plants survive these catastrophic events?
Plants living in these highly flammable environments survive by retreating underground, developing large underground storage organs that resprout rapidly after a burn. Non-grassy herbs commonly flower in spring after a burn. They even flower before the rains starts, using the nutrients and moisture that were stored in their root systems. They flower and set seed before they are smothered by tall grasses.
Grasses survive in the same manner by storing the energy that was in the leaves, in an extensive root system. When the veld burns, no nutrients are lost and is available for use when the grasses resprout.
There are even underground trees that can be thousands of years old. These plants have massive underground branches that are protected from surface fires. The leaves are borne on short stems that resprout from the buried branches after fires. Underground trees (geoxylic suffrutices, if you want to be technically correct) have close relatives that are true trees. For example, the underground cousin of the Buffalo thorn, Ziziphus mucronata is Ziziphus zeyherii.
So, what are the consequences if we do not emulate these natural processes?
The first consequence is that our healthy grasses start dying back. They are smothered by old grass leaves that surround the plant (known as moribund) and this moribund also inhibits the germination of seeds (excluding tree seeds).
When veld is overgrazed, there is not enough energy stored in the roots of the grasses to ensure their survival through winter.
The second, and very serious consequence, is that trees will sprout uncontrollably and turn our grassland into savannah. The tree’s shade also kills off the sun-loving grasses and that leads to poor soil cover.
The most tragic example near us is the Springbok flats north of Pretoria. In the writings of early explorers, they mentioned the abundance of animals on these plains. Today, virtually the whole area is covered by shrubs and trees with little grass cover left. Unfortunately, it is very difficult and very expensive to reverse this process.
How do we apply this knowledge in a grassland garden?
Ideally, one would still like to burn in early spring. A safe way to do this is to cut the grass and other perennials short, remove the excess material and then burn the area. Where it is not possible, at least remove the excess material to prevent smothering.
Burn in early spring, preferably after the first rains. This will ensure a cooler fire.
Remove unwanted saplings if the fire did not kill them off
It is claimed that many of the so-called pre-rain flowers will not flower if the grass has not been burnt. This is certainly not true of all of them since I have flowered many in my garden without burning. What is certainly true is that the flower display in early spring on a burnt patch is spectacular!
Only 2.5% of our grasslands are formally conserved and more than 60% are already irreversibly transformed. Our grasslands host over 4 000 plant species, where the majority of plant species are not grasses.
It is of utmost importance that we manage these fragile ecosystems correctly to avoid further plant losses. Even your garden can make a contribution.