Africa, Environment, Headlines, The Southern Africa Water Wire, Water & Sanitation

ENVIRONMENT-ZAMBIA: An Unwelcome Guest Has Taken Root

Newton Sibanda

LUSAKA, Dec 1 2007 (IPS) - An invasive shrub has colonised a corner of the Lochinvar National Park, upsetting the balance of one of Zambia’s most diverse ecosystems. Mimosa pigra, originally from Mexico, is now threatening wildlife and pastoralists who depend on grazing lands in and around the park.

“It’s a national disaster,” a consultative meeting of stakeholders in the nearby town of Monze concluded in its final report last month.

According to Highvie Hamududu, the member of parliament for the Bweengwa area in Monze, about 185 kilometres south-west of Lusaka, “Very soon, the grazing lands in this part covered by the infamous weed will not be accessible by our animals. Something needs to be done urgently; this is our cultural heritage.”

Lochinvar makes up a relatively small (428 square kilometre) part of the 7,000 square kilometre Kafue Flats floodplain, declared a protected wetland site under the Ramsar Convention – a treaty providing for international co-operation for the conservation of wetlands. Yet with over 400 bird species recorded, it is renowned as a bird watchers paradise.

Traditional leaders, local politicians and other community leaders attended the meeting in Monze, called to discuss the Chunga Lagoon Pilot site initiative which aims to restrict the spread of Mimosa pigra and to clear existing shrubs from the Kafue Flats.

The floodplain is fed by the Kafue River between the Itezhi tezhi Dam in the west and the Kafue Gorge Dam in the east. Within the flats, Mimosa pigra has mostly affected the southern banks of the Kafue River around the Chunga Lagoon.

The thorny shrub is found in many tropical and sub-tropical parts of the world. On the African continent it has posed special challenges in Ethiopia, Ghana and Uganda.

Since it was first noticed in the Kafue Flats in the early 1980s, Mimosa pigra has destroyed 2,900 hectares of pasture, and replaced it with impenetrable thickets that crowd out indigenous plants and animals.

It usually grows to just over two metres tall, but may reach heights of six metres. Under favourable conditions, these plants can grow up to one centimetre a day. In addition, their seeds can remain dormant in the ground for 10 years in the event of prolonged dryness, germinating when favourable conditions return.

“Large plants of the weed can produce vast amounts of seeds of up to 220,000 per year which are typically dispersed in two main ways: they are carried downstream during flooding, or transported by animals or machinery,” said Griffin Shanungu, co-ordinator of the Chunga Lagoon Pilot site.

According to William Lonsdale of the Commonwealth Scientific and Industrial Research Organisation, the meteorological data of Lochinvar National Park show that in the period from 1980 to 2005 there was a steady decrease in rainfall, while temperatures remained almost the same.

This has contributed to having a smaller proportion of flooded areas during the wet season, to the benefit of the Mimosa pigra plant, which does better on the fringes of the floodplain than in permanently waterlogged areas.

In addition, Lonsdale believes that the construction of dams at either end of the Kafue Flats has altered flooding patterns to the advantage of Mimosa pigra; there has been an insufficient release of water from the Itezhi tezhi Dam.

The director of the Environmental Council of Zambia, Edward Zulu, says the invasive weed is having a detrimental effect on many sectors of the economy, including agriculture and tourism.

Mimosa pigra is making it difficult for tourists to observe the Kafue lechwe (a marsh antelope found only on the flats) and to spot birds. Certain bird species endemic to the area, such as crowned and the wattled cranes, are endangered.

“The rich biodiversity of the Kafue Flats is under threat by the infestation of Mimosa pigra, which has significant impact on tourism by denying access to the area, also by making water availability very difficult and altering the scenery – but most significantly rendering the area almost mono-specific with regard to plants and almost completely devoid of wildlife which is the basis of the national park’s tourism,” said Zulu.

Tourists still visiting the park have also had difficulty finding places to spend the night, recently. “There is a critical shortage of accommodation in the Lochinvar National Park as lodge owners have abandoned the area,” said Hamududu.

Lodge owners are reluctant to establish tourist accommodation in the park because the Mimosa plant has been destroying the scenery. Hamududu said that the shortage of accommodation in the park has forced visiting tourists to spend nights in Monze.

As the spread of the plant continues to destroy the ecological balance of the Kafue Flats, local stakeholders – including the National Environmental Council of Zambia (NECZ) and the Zambia Wildlife Authority – have been taking steps to control the weed.

“As with most of the invasives, the three options available for preventing the spread of Mimosa is through mechanical, chemical or biological control,” said Brian Nkandu, national project co-ordinator at the NECZ for control of the invasive weed.

He said that about 100 hectares would be cleared this year, and 1,000 hectares by the end of 2009.