News agency, Cape Town, South Africa
Monday July 22nd 2019

City gives aliens the chop

In an attempt to preserve the rich biodiversity in the Blaauwberg region along the west coast of the Cape Town Metropole, the city has intensified its fight against invasive alien vegetation which poses a substantial threat to rare endemic plants and water purity.

Information supplied by biodiversity, environmental resource management for the city’s northern district regional manager Bongani Mnisi indicate that 621 hectares of land in the 1 400 hectare Blaauwberg Conservation Area (BCA) has been cleared of invasive Port Jackson (Acacia saligna) and Rooikrans (Acacia cyclops) over the last year.

Mnisi said the Blaauwberg region was rich in biodiversity, embracing a wetland that is home to 559 plant species, 42 mammal species and 140 bird species, 28 reptile species and four amphibian species.

Among the endemic plant species in the conservation area, three were critically endangered (Hermannia procumbens, and Serruria trilopha) two were vulnerable (Aspalathus acanthophylla and Ruschia geminiflora) and one was near threatened (Psoralea repens)

He said the clearing programme focused on the area between Big Bay and Melkbosstrand, extending inland from the R27.

“When it is complete the clearing programme will have rid the coastal section of 722.94 ha of invasive vegetation,” said Mnisi

He said Invasive Alien Species (IAS) are the second biggest threat after direct habitat destruction, to Cape Town’s biodiversity as they had a significant negative impact on the environment.

Additionally IAS also reduced water flow as it alien species sucked up much more water from the ground than indigenous fynbos species. IAS also produced more wood, increasing the “fuel load” which led to more regular and intense fires which led to greater soil loss due to erosion on burnt land.

Clearing IAS had cost the city R383 000 during the 2010/11 financial, he said.

Information sourced from Cape Nature indicate that IAS have invaded over ten million hectares of land in South Africa, with the Western Cape – which is also the region richest in biodiversity – the most heavily infested.

It is estimated that 43% of the Cape Peninsula is covered in alien vegetation, which consumes 7% of the Cape Floral Kingdom’s water supply and threatens up to 750 plant species in the province. — Peter Luhanga


Tags: biodiversity, Blaauwberg Conservation Area, Bongani Mnisi, Cape Nature, Invasive Alien Species

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