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Invasive Weed Threatens South Africa Rhino Sanctuary
Invasive Weed Threatens South Africa Rhino Sanctuary
Leon Marshall in Johannesburg
for National Geographic News
September 16, 2005
South Africa's oldest nature reserve is threatened by an alien invasion so fierce that environmentalists now fear for the renowned park's future.
Hluhluwe-Umfolozi Park has won world acclaim for its rhinoceros rehabilitation program, which brought the white rhino back from the brink of extinction and may do the same for the even more endangered black rhino.
But the park is being overrun by triffid weed(Chromolaena odorata), an invasive species from Central America. The plant spreads at such a rate—smothering indigenous vegetation and driving off animals—that it was named after the carnivorous plants from the 1951 sci-fi novel The Day of the Triffids.
Guy Preston, head of South Africa's anti-invasive program, says the weed's infestation could be catastrophic.
"The animals don't eat it, and if [it is] allowed to take over, they will leave," he said. "This will be the end of the world's third oldest park and with it will go about 3,000 jobs and millions in income for the region and the country."
"Like a Cancer"
The weed has already jumped from South Africa into Mozambique and Swaziland. It poses a growing threat to these countries, which lack the resources to fight the invasive plant.
The premier of South Africa's KwaZulu Natal province, home to the 237,216-acre (96,000-hectare) Hluhluwe-Umfolozi Park, has warned that triffid weed could destroy more of the region's parks and cripple the agricultural economy.
Triffid weed was unwittingly introduced to South Africa in the 1940s amid horse feed shipped from Central America.
"They are like a cancer," Preston said, speaking of the plant and other invasive species. "Mostly their big danger is that by the time you notice their spread it is out of hand."
Preston leads Working for Water, a government program that combines invasive plant eradication with job creation. Former South Africa President Nelson Mandela is the program's patron-in-chief.
The eradication project is now creating about 33,000 jobs a year, a boon to participating local communities in a country where unemployment and poverty remain formidable problems.
The program currently runs 300 projects in South Africa's nine provinces. Teams canvass infested areas to hack out and destroy invasive species. Participants receive skills-training and education.
Preston, who is also a member of the Global Invasive Species Program, says the South Africa government has voted a substantial sum of money to tackle the triffid menace.
But the problem with triffid weed and other invasive species in South Africa has generally grown so big that authorities are looking at new ways of getting the public more fully behind the anti-invasive program.
In some regions, nonnative plants from around the world have taken so well to their new habitats that they are posing a serious threat to the rich plant and animal life that makes South Africa the world's third most biodiverse country.
Water hyacinth and other plants are clogging up lakes and rivers and invading forests, mountains, grasslands, and vast semi-deserts. In addition, the alien species often pose a fire hazard, making vegetated areas more fire-prone and sapping the country's precious water resources.
Preston believes the anti-invasive campaign must become more nuanced to get the public support it deserves. "The emphasis needs to shift from what is necessary to what is feasible as well."
Demand for a more flexible approach may be seen Pretoria, the nation's capital, which is famous for its jacaranda trees.
The tree, an import from Argentina, was first brought to the city in 1880 and large-scale planting started soon after. A hundred years later, more than 50,000 jacarandas adorned the city's streets, parks, and gardens.
South Africa's parliament passed an act three years ago that declared 198 exotic species as "weed and invader" plants. The law provides for stiff fines and jail sentences for trading in or keeping the plans on public or private land, including suburban gardens.
Officials recently listed the jacaranda under a special category of invasive species, which allows the city to keep existing trees but not to replant them when they die. The idea was that attrition would gradually eliminate the water-hungry alien trees from the city.
But local residents have put up such a fight that city authorities may relent and allow them to replace dead trees.
Preston, of Working for Water, says the alien-invasive problem is so immense that it may well make sense to get the distractive fighting over the jacarandas out of the way.
"We need all the support we can get. We don't want to alienate people," he said. "Jacarandas are a problem, but not to the extent that they should be allowed to get in the way of the bigger objective. We have to box clever and rather ensure support for the fight against far worse species."
But in general authorities are not taking a more lenient approach. Cities employ municipal officers dubbed "plant police," who knock on suburban doors to inspect gardens. Errant owners get warned to remove listed alien-invasive plants or be charged.