THIS FEATURE IS FROM VELD & FLORA MARCH ISSUE 109 (1), PAGES 32-35
DECADE OF ECOSYSTEM RESTORATION
The power of palmiet
You can help restore watercourses by propagating palmiet with this step-by-step guide
Aug 15, 2023 | REPORT BY GEORGINA VAN BILJON. PHOTOS BY JOHANN VAN BILJON
The power
of palmiet
Above: During flooding, palmiet buffers riverbanks and protects the land beyond.
FROM STREAMS RUNNING THROUGH CITIES to rivers meandering through agricultural landscapes, people around South Africa are trying to transform our degraded river ecosystems. More extreme weather is predicted due to climate change and may influence flooding cycles.
To buffer these effects, we need to consider how natural systems work and how we can use indigenous plants to help us overcome these challenges. To make freshwater ecosystems healthier again, one of the tools in our restoration tool kit for use in the southern areas of South Africa is harnessing the power of palmiet (Prionium serratum), an endemic South African palm-like shrub that grows naturally in the Western Cape and up to southern KwaZulu-Natal.
WHY WE NEED PALMIET
Spreading urbanisation and expanding agriculture often result in rivers being forced into channels more and more instead of being allowed to meander. Narrower, single-channelled rivers tend to flow more quickly, making erosion more likely.
Rivers naturally form meanders, which take up more space, in their middle to lower reaches of a river where the water speed is slower and sediment may be deposited. They may also have side channels, which can help to absorb the impact of floods by reducing pressure on the main channel.
Large invasive trees lining riverbanks can also cause channelling and must be removed by law. These invasive trees can overshadow indigenous shrubs that help bind the soil. Livestock can overgraze stream banks, leading to soil erosion.
Riverbanks are often modified using heavy machinery and embankments (berms) built to prevent homes or fields from being flooded. In some cases, such manmade structures might be necessary but approval from the Department of Environmental Affairs is required by law.
Above: Planting palmiet seedlings can help the process of restoring watercourses.
SLOW THE FLOW
Reintroducing specialist indigenous plants such as palmiet is a more eco-friendly way to buffer the effects of flooding. Palmiet has the potential to slow water flow, increase sediment deposits, improve water filtration and bind the soil. This is why a few, mostly non-commercial indigenous plant nurseries are cultivating palmiet on a large scale to help rehabilitate rivers and wetlands.
In Cape Town, palmiet is being planted by Friends of the Liesbeek. Friends of the Rivers of Hout Bay are growing and planting palmiet along the Hout Bay river. Government and international funding is also enabling large-scale planting along the Berg and Breede rivers.
Palmiet growers include our company, Intaba Environmental Services, Worcester Field Reserve, which is under the wing of the Western Cape Department of Agriculture & Land Care and the private nursery at Spier wine estate. Further afield, palmiet is also grown in Genadendal.
Active restoration involves using a balanced mix of plant species belonging in that catchment and freshwater ecosystem. Choosing appropriate sites for planting palmiet involves considering the water system’s hydrology and landscape. Best practice is to involve a freshwater ecologist or restoration practitioner with good experience of such restoration projects.
How to propagate palmiet
1. USING ON-SITE CUTTINGS
Nearly 20 years ago, an article appeared in Veld & Flora in which Dr Charlie Boucher and Melanie Withers explained how they had restored some wetland areas of Du Toitskloof pass using cuttings made and then replanted at the same site after propagation. These are known as on-site or in-situ cuttings.
Following this method, you can have fairly large palmiet plants growing in a short time. The method can be labour intensive but works well if you are trying to grow only a small quantity of palmiet and do not have propagation facilities.
- Use a handsaw, sickle or panga to cut off palmiet branches about half a metre to a metre long.
- Root the cuttings in ponds or plant them into holes at the river’s edge, using rope or strategically placed rocks to secure them.
- Your cuttings will be more successful if you plant them when the water level is low because this gives the cuttings enough time to establish their roots before the next flood or high-flow event.
2. USING SEED
For producing larger quantities of palmiet, it is better to propagate them from seed.
- Follow the ecological restoration principle of harvesting seeds within the same river catchment where you are planting to ensure genetic integrity.
- In summer, between November and January, monitor the developing palmiet seed heads because the seeds ripen and are released in a narrow time period that varies from location to location and from year to year.
- Dry your harvested seed heads on racks out of the wind – the seeds are very fine and can blow away.
- The seed heads open as they dry and release the seeds. You might have to chip the remaining seed heads with an electric chopping machine and then sieve the mixture. Discard the coarse seed capsules or heads afterwards and keep the fine seeds for sowing.
- Sow the seeds on the surface of a moist growing medium – peat gets best results – in seed buckets or germination trays.
- Germination usually takes five to seven days.
- Keep the seedlings in a tunnel or covered with clear plastic bags to help them stay moist.
- Once the seedlings are one centimetre high, transplant them individually into larger seed trays.
- Larger seedlings can be placed in potting bags in an acidic, sandy medium.
- Plant the young palmiet plants along riverbanks, in the river bed or in wetlands in late spring or at the beginning of summer when the water is low or has dropped after winter rains. This helps roots establish themselves and reduces plants lost due to flooding.
- Within only a few weeks after planting, even small palmiet plants can withstand higher water flows thanks to their highly developed root structure.
Above: Palmiet flowerheads are dried to release the tiny seeds and soon form leggy seedlings.
CLEAN & FRESH
One of palmiet’s surprising attributes is its roots, which in seedlings are about double the length of its leaves. This helps plants establish themselves in environments where flooding cycles happen.
Since Rodney February of WWF-SA and Johann formed a Palmiet WhatsApp study group in 2017 to share information and growing tips, many more people have successfully grown and planted palmiet in degraded river and wetland ecosystems. If you would like to join in, see our step-by-step guide and WhatsApp Johann on the contact below to join the group.
Clean fresh water is essential to our wellbeing so any effort we put into rehabilitating the health of our freshwater ecosystems will have a positive impact on our future.
Georgina van Biljon (georgina@greenintaba.co.za) is consultant for Intaba Environmental Services and secretary of the African board of the Society for Ecological Restoration (SER).
Johann van Biljon (johann@greenintaba.co.za) founded Tulbagh’s Intaba Environmental Services and has been growing and using palmiet in river and wetland restoration for more than 15 years. Mail him for more information or if you are interested in joining the palmiet WhatsApp study group.
This article was featured in Veld & Flora in the March 2023 edition.
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