Voracious parasitic weed threatens Nepal's wildlife (Feature)

By Pratibha Tuladhar Jan 25, 2011, 5:41 GMT

Chitwan, Nepal - Some 200 kilometres south-west of the Nepalese capital Kathmandu, a non-native weed is rapidly destroying plants, with menacing implications for local wildlife.

The South American native is locally known as banmara (forest killer) or 'mile-a-minute.' It was first identified in Nepal in 1975. The weed grows about 2.5 centimetres a day and has covered large sections of the 932-square-kilometre Chitwan National Park.

'It produces up to 40,000 seeds a day, which are scattered in the forest by various means,' said Chanda Rana, researcher and maker of the film Mile-a-minute - A serious threat to the Chitwan National Park.

'If we don't make collective effort within five years, about 50 per cent of the habitat will be wiped out.'

Conservationists said the plant is one of the biggest threats to wildlife, besides poaching.

The area is home to the rare one-horned rhino and the endangered Royal Bengal tiger. Nepal has been battling rampant poaching of the animals, especially the rhino, whose horn is prized in China for its alleged aphrodisiac qualities.

The rhino population in Nepal stands at just over 400. More than 25 were reported dead in 2008-10. Nearly 100 were killed in 2001-02, when the country was at the peak of the Maoist insurgency.

Two years ago, the government initiated a biological control campaign to check the weed's growth.

'We induced a gall fly in the plants that ate up nodes and checked the growth,' said Ram Babu Paneru, senior scientist at the Nepal Agriculture Research Council. 'It worked to a point but lateral branches grew, so it was given up.'

In January 2010, Rana initiated a campaign to eradicate the weed, which the prime minister joined.

'The invasive plant is threatening the existence of flora, fauna and unique ecosystem of Chitwan,' Prime Minister Madhav Kumar Nepal said at the time. 'It is high time all should participate in controlling the invasion of the wild weed.'

Residents of the area surrounding the Chitwan National Park said the destruction of the forest habitat has caused the wild animals to venture into the buffer zone in search of food. Human deaths caused by wild animals there are reported frequently.

Conservationists said the creeper, rated as one of the worst invasive plants in the world, has engulfed more than one-third of the prime rhino habitat in the national park.

'The plant grows, covering all the other plants on its way, depriving them of sunlight and nutrition,' naturalist Prakash Neupane said.

'It is a serious threat to wildlife as it destroys their food and natural habitat.'

The weed lacks nutrition required by the herbivores that depend on nutrient-rich vegetation for their survival.

'I have seen rhinos and goats eat it sometimes, even though it is not a preferred food with the animals,' said forest guard Kul Bahadur Tamang. 'I don't know what the long-term impact of eating the plant would be on animals.'

There is no clear explanation of how the plant came to be in Nepal.

'We think the migratory birds carried them here in their droppings,' Neupane said.

'The plant makes the forest look ugly,' said Durga Prasad Tiwari, a nature guide. 'What used to be a lush green forest when I was growing up, now looks dry and barren as the creeper dies once it has used up the nutrition of the plants under it.'

Although a number of organizations have been researching a way to prevent the weed from spreading, there has been no real answer.

'It will take us another couple of years to identify the real problem,' said Naresh Subedi, research officer at Chitwan National Park.

'We have fitted satellite collars on herbivores to study the parameters of problems faced by them.'

Political instability has contributed to the problem. The period of Maoist insurgency, which ended in 2006, was a boon for poachers because the focus of security shifted from the forest to the conflict zones. Local residents accuse the government of not doing enough.

'If politicians talk about rhino conservation, they should talk about this, too,' said Tiwari. 'How will rhinos survive when their food is gone?'

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