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FEATURE

Aerial photo of water hyacinth

INVASIVE ALIEN PLANTS

RAND WATER’S CONTROL STRATEGY

AT THE VAAL RIVER BARRAGE RESERVOIR

Invasive Alien Plants (IAPs) refers to plants that are non-native to an ecosystem,
which may cause economic and environmental harm or adversely affect human
health. Particularly, they impact adversely on biodiversity, including the decline and/

or elimination of native species, through competition, predation or transmission of
pathogens. This results in the disruption of local ecosystems and their functions.

nvasive alien plants introduced and/or
spread outside their natural habitats have
Iaffected native biodiversity in almost
every ecosystem type on earth and are
one of the greatest threats to biodiversity.
Such invasions are among the top drivers
of biodiversity loss and species extinction
around the world, with invasive species
having contributed to nearly 40% of all
animal extinctions, as suggested in a
study done by Bellard, Casey & Blackburn
(2016). The problem continues to increase
greatly from an ecological, socio-economic
and health point of view, worldwide.
Invasive alien plants exacerbate poverty
and threaten development through their
impact on agriculture, forestry, fisheries and
natural systems – which are an important
basis of peoples’ livelihoods – particularly in
developing countries like South Africa. This
damage is aggravated by climate change,
pollution, habitat loss and human-induced
disturbance.
IAPs are not static and can be introduced
to a new water source from one that is
impacted by birds, humans, boats, jet skis
or any moveable object, via the transfer
of IAP seeds, seedlings or plants. These
can regrow asexually (i.e. vegetatively)
and sexually (i.e. seeds), allowing for
exponential growth in the new water
Development stage of water lettuce Megamelus feeding on water hyacinth source. Environmental factors such as wind
and poor water quality (i.e. high organic

10 Landscape SA • Issue 135 2024 Check us out www.salandscape.co.za