PALMIET: tHE NATURAL ENGINEER OF RIVERBANKS

​A few weeks ago, the Conservancy staff attended the annual fynbos forum which was hosted online. Our manager, Aileen Anderson, was presenting at the conference and so we were all able to participate in the on line conference. 

​During the conference, Intaba environmental services gave an informative presentation about their nursery, and what caught our attention was the palmiet plant (Prionium serratum) and how they rehabilitate unnaturally degraded riverbanks.

​We found the fynbos forum, especially the rehabilitation aspects, to be very interesting. We are currently in the process of relocating and establishing a new nursery at the new offices. As the nursery is established, we will apply new concepts and methods to cultivate trees and vegetation for our restoration activities.

​As part of the fynbos forum, Twakkie and Zaniel went on a fieldtrip to Intaba environmental services (Tulbagh)  This allowed us to experience and engage more with the team We came away with so much knowledge that we can now apply and put into practice within the conservancy. 

​Most importantly, the cultivation and use of palmiet which we will discuss in this blog.

Palmiet (Prionium serratum) ready to be planted out.

Characteristics of Prionium serratum (Palmiet)
The leaves remain encircle (Boucher, 2004) which means that the stems of the palmiet plant branch, and the remains of the previous stems protect the plant from injury during floods, when rocks and stones migrate down rivers and can smash the stems (Boucher, 2004). The plant has dense stems that seem to be a grouping of separate plants but are really interconnected stems, usually originating from one initial plant through vegetative reproduction. The grey- green, shaped pointed leaves can be 1.2 meters long and 30-40 meters wide, crowed together in rossetes at the end of the stems (Boucher, 2004) (September to February) (Boucher, 2004).

​Palmiet usually grows about 2 m high and is found from Western Cape to Kwazulu Natal in marshy areas, streams, rivers, and riverbanks and large dense strands http://pza.sanbi.org/prionium-serratum. Palmiet grows in swamps and riverbanks, whereas palmiet wetlands are wetlands where palmiet grows and qualify as ecosystems that reduce floodwater erosive damage.

The many benefits of palmiet in the ecosystem

Palmiet is a fascinating plant that acts as an ecosystem architect (Rebelo, 2019). The plant is excellent in providing habitat for fish, birds, and insects (Boucher, 2004). Palmiet stabilizes riverbanks from erosion http://pza.sanbi.org/prionium-serratum. Palmiet wetlands have built up layers of peat and organic material with high layers of carbon content Palmiet wetland conservation | Farmer's Weekly (farmersweekly.co.za). Palmiet wetlands can improve water quality because the thick layers of palmiet act as a pure carbon filter for the water. The leaves of the palmiet act as a sieve, retaining chemicals and bacteria in the wetland. The plant has a thick root that keeps the plant from being ripped out during heavy rains. The flatness of palmiet allows the water to slow down. Palmiet wetlands act as a giant sponge, collecting water during the rainy season and releasing it during the dry season. Wetlands also slow surface flow, allowing groundwater aquifers to recharge.

​Rapid population growth and expansion of human activities is increasing the amount of waste and pollution (Naidoo,2005) and is endangering wetlands. Changes to wetlands can have far-reaching consequences (Boucher, 2004). Palmiet (Prionium serratum) is declining in some habitats because of degradation, of habitat from overgrazing and frequent fires http://pza.sanbi.org/prionium-serratum. Other threats to wetland or palmiet wetlands may be additional water abstraction as well as pollution and invasive alien plant infestation (Branch,1984) (Rebelo, 2019).

A team planting out palmiet in the Duiwenhoks river as a rehabilitation project.

​The removal of palmiet leads to the damage of wetlands. The absence of palmiet causes greater flood damage, more severe erosion, and dam silting. If palmiet is removed, water may become contaminated because of the filter provided by the thick layer of palmiet that is no longer present. If palmiet is taken out of rivers, open water bodies will result in high evaporation and water loss. The absence of Palmiet results in greater flood damage, severe erosion and silting up of dams Palmiet wetland conservation | Farmer's Weekly (farmersweekly.co.za). 

It is a myth that palmiet clogs rivers and impedes water flow. Palmiet is said to clog streams by filling them in their natural state. This assumption may be based on the tendency of immersed stems, anchored on the riverbank's borders to bend outwards into the channels as water levels fall during dry spells (Boucher, 2004). It may therefore appear as if palmiet is invading the rivers, even though the stems will normally fold back against the banks when water levels rise and flow velocities increase (Boucher, 2004).

The best time to propagate this plant is during the winter months. The plant can be reproduced and developed from divisions, and because it is a semi-aquatic plant, it requires a moderately damp environment to thrive. http://pza.sanbi.org/prionium-serratum. This plant can be planted and nurtured in our nurseries.

In terms of healthy wetlands, the conservancy runs an initiative that involves alien removal along rivers to improve the quality and quantity of water. Other monitoring programs include river monitoring as part of GASPP (Grootvadersbosch Aquatic Species Protection Project), which includes the SASS (South African Scoring System) and fish monitoring. This monitoring study also allows us to investigate other features of the rivers, such as water quality, pH, and temperature etc.
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We can all work together to promote awareness and maintain our wetlands. Palmiet is a crucial species to protect in our rivers systems. We can work together to raise awareness and communicate the wonders of this wetland plant.   
 
Please leave a comment if you have any other thoughts or suggestions.

References

Boucher, C. and Withers, M., 2004. Palmiet. Veld & Flora, 90(1), pp.26-28.

Branch, GM & Day, J.A., 1984. Ecology of southern African estuaries: part XIII: the Palmiet River estuary in the south-western Cape. African Zoology, 19(2), pp.63-77.

http://pza.sanbi.org/prionium-serratum

Naidoo, K., 2005. The Anthropogenic impacts of Urbanization and Industrialisation on the Water quality, Ecology and Health status of the Palmiet River catchment in Durban, KwaZulu-Natal (Doctoral dissertation).

Palmiet wetland conservation | Farmer's Weekly (farmersweekly.co.za)
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Rebelo, A.J., Morris, C., Meire, P. and Esler, K.J., 2019. Ecosystem services provided by South African palmiet wetlands: A case for investment in strategic water source areas. Ecological Indicators, 101, pp.71-80.