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Lantana camara action

Two million gallons of water per second plunge over the Victoria Falls on the Zambia Zimbabwe border, making it one of the world's most spectacular waterfalls. But the lush rainforest surrounding the Falls, or Mosi-oa-Tunya as it is known locally, is being threatened by invasive weed species Lantana camara.

Lantana
Lantana

The weed, which is native to Argentina, was introduced as an ornamental shrub, but grows so rapidly in Africa that it can form dense, impenetrable thicket that replaces indigenous vegetation. Growing up to two metres in height, it can even smother trees, impacting on local biodiversity and reducing the amount of food available to stock or wildlife. There are more than 50 varieties of the flowering shrub in Southern Africa. They vary in appearance between different localities, but common features include stems covered with short stiff hairs and curved prickles. Its dark green leaves are hairy and rough which produce a pungent odour when crushed. Seeds are pink, red, crimson, orange, or yellow in compact flat-topped heads. In moist areas the plant flowers all year round and produces small berries, which are attractive to birds that eat them and then disperse the seed.

Lantana camara is classified as a 'transformer' - the most damaging type of environmental weed. These plants can dominate or replace any canopy or sub-canopy layer of a natural ecosystem, thereby altering its structure. It is particularly difficult to control, as it is a perennial plant that will regrow to form denser thickets if it is just slashed and left. Instead, a combination of mechanical and chemical control is best, explains tour operator and botanist Steve Bolnick. "Seedlings and isolated small plants up to a metre tall should be uprooted by hand pulling, either when the soil is moist or after first loosening dry earth with a hoe, pick, mattock, or fork," he says. "For larger plants and dense thickets, top growth should first be cut away with pangas to expose the base of the plant which should then be felled to the ground." The herbicide Roundup is registered for use against Lantana, but will also kill other green plants including grasses. It is usually applied as a spray at a concentration of one to two per cent in clean water.

It is not just environmentalists that worry about the invasion of the Victoria Falls Rainforest by Lantana. The area, which is a World Heritage site, depends heavily on tourism and some believe that by affecting its beauty, the weed also threatens its appeal to tourists. So the Zimbabwe Tourism Authority (ZTA) and other representatives from the industry have also been involved in the clean up operation, explains the ZTA's Pauline Ndlovu. "If we do not keep the rainforest as naturally as possible, we will lose tourists." And with all the problems in Zimbabwe, the local community needs to keep hold of the lifeline that tourism offers.

With contributions from: Busani Bafana

Date published: January 2004

 

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