Eco Bites

The Typha Take-over

Bulrushes are taking over. In many of the reedbed areas around Rietvlei bulrushes are displacing other wetland plants, and in the Dolphin Beach ponds the water area is gradually disappearing under bulrush growth. What is this reed and where does it come from? There are 11 species of Typha world-wide, most occurring in the Northern hemisphere; in addition there are several hybrid species. Typha latifolia is the most common species and occurs naturally on all continents except South America and Australia, but it has now been introduced there.  Typha capensis is common in southern Africa, and is the local species found in many of our wetlands. The reed has many common names in different parts of the world, we know it as bulrush, cattail, or by the British name reed-mace. Although often a nuisance, they are extremely efficient in removing nutrients from water and are thus very effective filters. Bulrushes grow in wetlands, lakes, river courses, estuarine habitats and even in marshy coastal habitats which is predominantly fresh water. When conditions favour Typha they form dense monocultures, spreading rapidly by vegetative reproduction forming thick mats of rhizomes and plant litter. This impacts on other species by changing the habitat and forcing other plants out; they can rapidly close open water giving other plants few opportunities to establish. Typha seeds are dispersed by winds, in water, on the feet of birds and livestock, or by humans and machinery. Uses of Typha However, Typha is also a very useful plant and is used for many things. It is used as thatch for roofing; woven into mats, chairs, hats, etc; it is a source of fibre for rayon and a greenish brown paper; it is used as torches and tinder for making fires; the flower clusters are used for stuffing pillows and mattresses, and for insulation, dressing wounds, and lining diapers. Typha stands provide important food and cover for wildlife and birds, establishing habitat for many waterfowl. Many parts of the plant is also edible for human consumption and are an important source of protein in many parts of the world; rhizomes are dried and ground into flour or eaten as cooked vegetables; young stems are eaten raw or cooked; and the pollen is used in baking. Because of its very effective water filtering properties, Typha is widely used in artificial ponds to filter effluent and stormwater runoff in many parts of the world, including Cape Town. Controlling Typha Controlling excessive Typha growth is extremely difficult and can be quite costly, particularly in natural systems. Various methods have been tried and tested all over the world, but there is no easy way to control the plant. Herbicides can be effective when applied while the plant is flowering, but the disadvantage is that the decaying plant material accumulates and results in hypertrophic conditions, this plant material also provides a good substrate for regrowth of Typha. Some herbicides may also have negative effects on other plant and animal life in the system. Mechanical removal is difficult because of the depth and volume of the rhizomes, but it can be effective in reducing the size of infestations. Manual removal works best on small seedlings when they can be easily pulled out of the damp soil. The best way to control Typha seems to be using fire and physical cutting in conjunction with flooding. If the reeds are burnt and/or cut when water levels are low, and then flooded, growth is considerably inhibited. An effective control can be achieved by a combination of mechanical and hand cutting at the end of the growing season and when water levels are low, two clippings about a week or two apart will achieve best results, but then the cut area must be submerged as soon after in at least 8 to 10 cm of water when water levels rise again. Something will have to be done about the Typha growth in certain areas of Rietvlei, but any control operation will be costly and time-consuming. Using fire will help a great deal, but there are inherent dangers that must be considered. Access to the affected areas for cutting or mechanical control is not always easy and further complicates control operations. Compiled by Niel van Wyk from various sources.