Over 9,000 species of alien plants, trees and shrubs are colonising and destroying the fragile South African environment. The government now is cracking down hard on owners of gardens and plantations whose alien plants cause so much damage.
Gardeners countrywide now are being ordered regularly by municipal officials to remove all their 'alien' trees, shrubs and plants. Schools regularly embark on programmes to chop down all the alien tree invaders along the country's rivers and streams -- and every year between December and March, during their flowering season, tons of purple pompom weeds are pulled out from their roots along the roadsides and parks.
The previous SA government had already recognised this alien plant invasion as a major environmental hazard. They launched an eradication programme of a great many alien plant species from 1983. See
Gardening centres responsible for 62% of alien invader species:
Gardening centres and nurseries are also very actively encouraged to switch their sales stocks to indigenous plants, trees and flowers -- because they are responsible for 62% of all the alien plant invasions in South Africa.
One hapless homeowner in Pretoria (see video above) last year was trying to remove a gigantic palm tree which had outgrown his garden - and thought up a plan which somehow didn't work out as well as he'd wanted to. Gardeners can be seen all over South Africa - cutting down their beloved flowering Acacia trees from Indonesia and the gigantic Australian eucaluptus trees - although its leaves often are used by tribal doctors in a variety of medicines, this majestic tree with its shedding bark also is infamous for its ability to suck up every drop of water within a 50 metre-radius - withering every other plant trying to survive in its vicinity.
The SA government budgeted US$ 100-m between 1995 and 2000 to the Working for Water Programme, which is spearheading the control of the invasive species.
One of the more distinctive and most stubborn plant invaders are pompom weeds (a South American daisy, Campuloclinium macrocephalum). Pompoms are the distinctive hand-held ornamental tufts that have been made famous by American cheerleaders. They bring connotations of applause, goodwill, possibly even excitement.
Pompom weed also invades South African grasslands at a massive rate, threatening both nature conservation and agriculture. It's definitely outstayed its welcome: it is rapidly displacing native species, reducing biological diversity.
Infestations become conspicuous when the plants are in flower, usually between December and March, transforming the landscape from green to pink. The plant initially establishes itself in disturbed sites, such as roadsides, but then invades grasslands, open savanna and wetlands.
All the provinces suffer from pompom-weed invasions. So when it's in flower and highly visible between December and March, entire armies of environmentalists and school children are enlisted to pull the plants out by their roots.
Also, while the pine-tree and wattle plantations are also seen as valuable income-generating enterprises, their owners now also have to see to it that their plants and trees do not invade the surrounding environment - and pay to keep surrounding areas clear of seedlings. The two largest invader species in this regard are the central American pine -- pinus patula mostly and the black wattle from Australia, the Acacia mearnsii de Wild.
Pinus patula was first introduced into South Africa in 1907. Around 1920, the species was also introduced into Zimbabwe and Zambia, where it failed.The species started flourishing in Zimbabwe only from 1934 -- and by 1970, a total of 36,000 ha were planted with it, a full 74 percent of all the planted pine forests in Zimbabwe.
In South Africa, some 223 600 ha were planted in 1970 and by 2001 they form forests totalling 337 000 ha, mostly in the cooler areas of Mpumalanga and Kwazulu-Natal provinces.The species is an aggressive invader, and has overpowered many Afromontane forests, miombo woodlands, and grasslands.
An even worst culprit is the black wattle from Australia, the Acacia mearnsii De Wild. While it remains a shrub in its homeland, in South Africa it grows into trees and is a very aggressive invader species.
People planted the wattles from about 1864 for use in the tanning industry - and it's still used for this purpose today.
It's a very aggressive coloniser, overwhelming indigenous plantlife rapidly: a pod normally contains an average 7 very light seeds -- about 48,600 to 70,200 seeds per kilogram. It begins to flower at about 20 months from seeding, which spread by running water, and it flourishes after wild-fires: the heat from fire improves seed germination. One hundred years after first introduction there were close to 324 000 ha, but since the eradication programme, there's still some 132 000 planted hectares left.
They have also invaded some 2,5-million ha of land in South Africa - and to eradicate these and then keep them under control is estimated to cost about US$1,600-m.
Plantation species are blamed for 38 percent of all the alien plant invasions in South Africa - the rest come from gardening centres which distributed species for hedges, ornamental use, shelter, shade and fixing or stabilizing sand dunes. Large South American grass species also were especially adapted to the acid conditions of gold mine dumps and planted on the large wasteland sites in large patches, in attempts to reduce the heavy air pollution containing this acid-laden yellow sand.
In fact most gardening centres in South Africa until about ten years ago, did not sell anything else except foreign plants, trees and shrubs for years - with particular favourites the Indonesian flowering Acacias, the Japanese Cherry and the north African palm tree varieties.
And that's where that big palm tree on the video also came from.