THE IMPORTANCE OF GRASSES
“The role grasses play in nature and our lives…”
A visit from Frits van Oudtshoorn, author of ‘’GUIDE TO GRASSES OF SOUTHERN AFRICA“to CCJ Woodmead in December has prompted me to write about grasses and about the grasses we have now identified on the Greater Woodmead Estate (GWE).
Frits’ visit was one of those things you dream of. Had I done enough work to be prepared for his impending visit? All he suggested I needed for our day in the field was a bucket with water to keep the grasses we sampled fresh, a plant press, so that once we had collected the grasses we could put them in a press to preserve them.
I began collecting for this visit a year ago. Why so long ago you may ask? Well the visit was planned for last year and so when I opened my grass press to really get it organised for his visit I was positively mesmerised at what I had already collected and how absolutely beautifully preserved all the pressings were. Further, I am beginning to realise more and more as I explore our grassland just what a surprising variety of grasses we in fact do have. Frits’ visit bore this out. Our collection for that one day was 39 different grass species.
Grasses are certainly different things to different people. This is fine as long as we all are clear about the important role they play in nature and in our lives. Simply, grasses are important in 3 respects – they are an important source of food for man; they play an important ecological role in nature; and they are good protectors of the soil against soil erosion. It has been said that if all the plants on earth were to disappear and only the grasses remained, man would still be able to survive. Grasses are flowering plants which, because of their adaption to wind pollination, have flowers that are considerably reduced in size and lack the colourful bracts so typical of many flowers. Grasses belong to the family Poaceae, which is the fifth largest plant family on earth. Grassland is the second largest biome in South Africa.
The greatest value of grass is perhaps the role that grass plays in stabilising and protecting the soil and for this reason the grass family is probably the most important plant family on earth .Today South Africa is faced with its grassland biome being under serious threat, mainly from urban encroachment.
Most of South Africa’s grasslands are found in highveld areas that experience frost in winter. The plants found here on our highveld are adapted to survive fires and the grassland biome is very rich in plants, with nearly 3800 plant species recorded. In the past, grasslands were home to large herds of animals, but today these animals survive in nature reserves and on game farms. Grasslands are rich in birds, many of which like our guinea fowl and spur fowl eat seeds. Nearly half of our original grassland biome has been ploughed to plant maize, sunflowers, sorghum and wheat. Most of the Gauteng highveld is home to a grassland biome and much of this region has been developed for mining, industry and urban development. Urbanization is the major influence on the current loss of natural areas – the Witwatersrand is centred in this biome. The grassland biome is considered to have an extremely high bio-diversity, second only to the fynbos biome. Rare plants are often able to flourish in grasslands.
Several interesting Grassland Biome facts:
* 25 per cent of the Earth is covered by the grassland biome
* There is a grassland biome on each continent with the exception of Antarctica
* Periodic fires, whether they are induced by man or occur spontaneously, are very important to the grassland to ensure that invasive plants do not take over
Grasslands, (also known locally as grassveld) are mostly devoid of trees, except in a few localised habitats. Bulbs (geophytes) are often abundant. Frosts, fire and grazing maintain the grass dominance and prevent the establishment of trees.
There are 2 categories of grass plants: sweet grasses and sour grasses.
*Sweet grasses, maintain their nutrients in the leaves in winter and are therefore palatable to grazers.
*Sour grasses; tend to withdraw their nutrients from the leaves during winter so they are unpalatable to grazers. Sour grasses tend to be found where rainfall is higher, in mist belts and on more acidic soils.
We at Woodmead have quite a lot of sour veld.
Grasses were the first plants to be cultivated as food at least 10 000 years ago – wheat is a type of grass. Livestock, antelope, birds, rodents, insects are dependent on grass as a source of food. Southern Africa is exceptionally rich in palatable grasses. Grass plays an essential role in nature, especially as a source of food, but grass provides shelter and nesting material and usually it is the animals at the bottom of the food chain that utilise grass. Here on the GWE where we don’t have grazers we see the smaller animals, like the rodents, rabbits, ground squirrels eating grass seeds and nibbling on the base of the grasses. The reserve nutritious matter is stored in the base of the grass culms, making this a very nutritious part of the plant, and very good reason why this is most favoured by these little creatures.
The seed eating birds, finches and the doves eat mainly grasses with round seeds and probably play an important role in the dispersal of these seeds. Weavers (like the sociable weaver) and finches need grass to build their nests. The many insect species rely on grass for food and shelter. On the estate we have very active termite numbers. They consume large quantities of grass material and as a result we have very little thatching (moribund) material. The Harvester termites or fungus growers cut the grass culms, leaves and other organic material up into short pieces and carry them to the bottom of their nests. This material is planted in ‘gardens’ and used to cultivate fungi, which serve as food and results in our very special ‘termite rich islands‘throughout Wilds East and Wilds West. Growing on many of these very old termitaria is a large tree enjoying the readymade compost garden.
Grasses are known for being particularly effective in combating soil erosion. Grasses are also tough plants that can survive in difficult conditions. Grasses break the speed of runoff rainwater, also breaking the impact of raindrops and in so doing avoid a hard ground crust forming on the surface of the soil.
Grasses, assist in keeping the soil temperature cool against the sun, and protects the soil against the wind so improving the moisture retention quality of the soil which ultimately protects the seed bank.
Sensitivity to specific conditions makes grasses good indicators of veld conditions. Scientific ways of determining the condition are done but here in the GWE, in areas we refer to as being pristine bushveld the bio-diversity of plant and grasses just indicates what a very precious piece of land we have right here on our doorstep. There are only two other areas in the Greater Johannesburg region as rich in diverse vegetation like ours and that is the Melville Koppie region and the Linksfield Ridge region.
So, when next out walking, take some time to scratch in and around any tuft of grass and you will be quite amazed at what a diversity of life it is supporting. We tramp blindly through the veld, over the grasses completely unaware of what and who is living there. Here, from December through to March, the GWE grassland areas display a mix of grasses with such interesting names like; Common finger grass, Brown Rhodes grass, Gum grass, Wool grass, Spreading three-awn grass, False love grass, Heart-seed love grass, Caterpillar grass, Spear grass, Wire grass, Black-footed grass, Velvet signal grass, Hairy trident grass, Cottonwool grass, Herringbone grass, Guinea grass, Pincushion grass and Rat’s -tail dropseed grass to mention a few.