City declares war on alien invasive vegetation
23 March 2017
Johannesburg City Parks & Zoo has over the past six months cleared more than 110ha of open spaces, rivers, dams, lakes and protected areas in a massive drive to rid the city of invasive alien plant species clogging waterways and causing serious damage to natural environments.
Since its launch in October 2016, the City’s Alien Invasive Species Eradication Programme has resulted in the destruction of 30ha of identified problematic plant species in Helderkruin, Roodepoort; 25ha in Albert’s Farm; 20ha in Juweel Park along the Klein Jukskei Spruit; and 35ha in Vorna Valley, in Midrand, and Ebony Park.
“As the custodians of the green environment in the City of Johannesburg, we have over the years engaged in several programmes to remove alien invasive plant species in our commitment to preserving our open natural environments,” said JCPZ Spokesperson Jenny Moodley.
“Our most recent programme has seen our crews, together with Extended Public Works Programme (EPWP) teams, blitz and clear vast areas of these identified plants, including weeping willows, bug weed, grey poplars and black wattles.”
Moodley said there were 200 species of plants declared as weeds or “invaders” in South Africa. She said JCPZ’s mandate was that all declared plants growing within 30m of the flood line of a river or waterbody must be removed.
Of the 200 known problematic species, Johannesburg is particularly affected by the silver wattle, black wattle, Australian blackwood, weeping willow, moth catcher, Spanish reed, pompom weed, queen of the night, pink berry, water hyacinth, saligna gum, lantana, bugweed and white poplar, to mention a few.
“Our approach to combating alien invasive species is by detecting them at an early stage and eradicating them before they become established,” said Moodley.
Moodley explained the devastating effects of an alien invasive species such as the weeping willow tree on the environment.
“Salix babylonica or weeping willow is native to China and is most commonly found along water’s edge in parks and large landscapes because of its love for moisture. It’s an invasive species because of its roots system, which naturally grows towards water.
“Weeping willows can spread roots into the bed of a watercourse, slowing the flow of water and reducing aeration. Trees form thickets that divert water outside the main watercourse or channel, causing flooding and erosion where the stream banks are vulnerable.
“The leaves create a flush of organic matter when they drop in autumn, reducing water quality and available oxygen, directly threatening aquatic plants and animals. These factors, together with the amount of water willows use, can damage stream health,” she said.
The Alien Invasive Species Eradication Programme will continue until June 2017. The areas to be blitzed will be published on the JCPZ’s Facebook and Twitter accounts.