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ENVIRONMENTAL FEATURE

There are multiple benefits associated with Practical lessons learnt about
establishing the appropriate indigenous riparian rehabilitation
plants along river banks. Investing in a Eradicate your invasive plants and remove
biodiverse landscape may act as a buffer threats to rehabilitation efforts. Learn about
against climate change and help to counteract invasive alien plants (IAPs) and ensure
the impacts of extreme weather conditions that you follow the alien clearing methods
like flooding. In other words, increasing recommended on the ‘Working for Water’
biodiversity also increases the system’s website. Specific herbicides and dosages
ability to absorb and adapt to stresses. Other are registered for different plant species
benefits of rehabilitation are habitat creation and growth forms, so stick to these specific
for pollinators, which support fruit production chemicals and dosage rates. If you are not
in adjacent agricultural landscapes. Likewise, sure how to identify the plant species, use an
an increase in predatory insects that can app like iNaturalist, check out PlantZAfrica,
take refuge in these biodiverse rehabilitated consult your local Department of Agriculture
areas can act as natural pest control against representative or contact SANBI’s Directorate
aphids and other agricultural pests. Soil of Biological Invasions. Understanding
micro-organisms (like Collembola) thrive in the potential threats to your rehabilitation
healthy ecosystems and boost soil health. efforts is key: is there livestock overgrazing
Restored riparian zones act as corridors for in the riparian zone? Are there too frequent
the movement of species across a landscape fires? Is there an altered hydrology due to
and these interconnections also strengthen over-abstraction? Find out the cause of the
ecosystem resilience. degradation, what is driving it and whether it
can be mitigated.
How to rehabilitate riparian zones
Firstly, contact a rehabilitation specialist to Understanding river bank dynamics, flooding
assist in devising a tailor-made plan suited and local systems is necessary, as there are
to your site conditions. Riparian zones are different zones along a river bank, secondary
highly dynamic, and a holistic understanding channels and various other hydrological
of geomorphology, hydrology, botany and and geomorphology aspects that need to
horticulture is needed in order to restore be considered when rehabilitating riparian
them. Attempting to do it oneself may seem zones. Certain plants are suited to the wet
like a less expensive option but can lead bank zone and can be completely under
to some regrettable issues, and ultimately water in flooding season, while others are
end up costing considerably more than better established in the dry bank zone
professional advice upfront. Remember, that is flooded only rarely, e.g. during a 1:20
experts have had years of experience in the year flood event. Seek to understand the
field and have learned many lessons that help abiotic (climate, soil, etc.) and biotic factors
ensure the success of subsequent projects. (vegetation type, keystone species etc.) in
Johann van Biljon from Intaba Environmental the system, as they all have an influence on
Services says: “We have worked with many how you undertake rehabilitation. The more
landowners undertaking river rehabilitation you know about your natural environment,
over the past ten years. One landowner the more you will be able to best navigate the
Natural river unfortunately planted Bottle Brush trees task ahead.
ecosystem in (Callistemon viminalis) after alien clearing had
the fynbos already taken place. These trees are a listed Reshaping of modified or unnaturally
biome invasive species, so utterly inappropriate as a shaped riverbanks (caused by erosion or the
restoration species (not to mention unlawful). historical use of machinery) is sometimes
Another landowner planted hundreds of necessary, but a challenge to correct. This
indigenous trees on second hand drippers ‘hard’ rehabilitation methodology may
from his vineyard and lost nearly all his trees involve the re-shaping of banks using
due to irrigation failure in summer”. machinery, construction of gabion walls,

A planted riparian forest, approximately nine years old A rehabilitated river bank on the Kleinberg River, Tulbagh

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Landscape SA • Issue 113 2022 15