Asia-Pacific, Environment, Headlines

SRI LANKA: Invasive Plants: Yet Another Environmental Menace

Amantha Perera

COLOMBO, Nov 17 2009 (IPS) - Ask any Sri Lankan, and he or she will cringe at the mention of ‘water hyacinth’, infamous in the country, where it is called by its more common local name ‘Japan Jabbara’. The weed-like water plant has spread across the island, and everyone knows its potential to take over any watery home in double quick time.

Its history is long but nasty on this island state. It first arrived in the country in the company of dignitaries in 1901, when the wife of the then Colonial British Governor, Lady Blake, brought it to Sri Lanka. She, according to environmentalist and lawyer Jagath Gunewardena, sought the help of the main botanical garden to grow the seeds.

“Then it spread. I guess everyone wanted to keep the plant that was brought by the governor’s wife,” Gunewardena told IPS. A century after it has been tagged as the worst weed invasion on the island, a protective law, called Water Hyacinth Act, was enacted to prohibit not only the entry of the plant after which it was named but all other alien plants into the country.

Water hyacinth, with its thick green leaves and bushy roots, has spread all over the island, and no one has come up with a proper method to stop its menacing spread.

“That was how it came here,” said Sajeewa Chamikara, the coordinator of Sri Lanka Environmentalists Association (SLEA), which lobbies for tougher environment protection laws and carries out national environmental awareness programmes. “Now it has spread all over the island.”

The plant now covers acres of waterways, paddy lands and marshes, making it impossible for other plants to survive and blocking sunlight out, which in turn makes it difficult for fish to survive.


“It is the worst case of an invasive plant alien to the ecosystem that we have had,” Chamikara said. Problems posed by alien plants do not stop with the commonly known water hyacinth, according Chamikara and other environmentalists. It is but the start.

There are many that have followed Lady Blake’s infamous import, and are wrecking havoc on the island’s ecosystem. Gunewardena estimates that there could be as many as 40 alien plants that are spreading fast on the island. To make matters worse, no concrete measures have been taken to stop the spread and to stem the arrival of new environment-threatening plants.

“What happens is that most of these plants arrive in the country through humans; the majority are brought here as ornamental plants. People have no sense that a plant looking nice may not fit into our ecosystem; worse it could harm it,” Chamikara said. When the plants either grow out of control or become popular, within no time they take over vast areas and damage the ecosystem.

“They arrive as ornamental plants, but once they start growing fast, people just take them off and throw them, then they grow wherever they land,” said Gunewardena.

Chamikara takes the example of another alien invader plant, ‘Kaha Deya Para’ (with no known English name), which is spreading fast in the wetlands. The plant has spread so fast that near the town of Rathnapura, located some 100 kilometres from Colombo, there is a large stretch of land covered entirely by it.

“It can suck out the nutrients from the soil very fast, making it difficult for other plants (to live),” Chamikara says. That is not the only problem caused by the pesky invader—its preferred haunt is near waterways, and neither the plant nor discarded stems and leaves decay quickly. “They can block the waterways; there is also the real threat of flash floods aside from the long- term environmental damage they can cause,” Chamikara said. The plant is spreading rapidly in the districts of Colombo, Kegalle and Rathnapura, across the slopes of the central hills.

Environmentalists lament that lack of public knowledge of the plant and its huge impact on the local ecosystem has led humans to become an unwitting tool in its spread, that is, by using it to erect fences.

Another such case is that of ‘Koster’s Curse’, a perennial or highly invasive shrub, which was introduced as an ornamental plant from South America. It has rapidly spread in the plains.

According to Chamikara the plant grows like a bush, blocking sunlight from other plants below it. “Its spread threatens indigenous plants that grow in the same areas,” he said. There are also fears that the rapid spread of the shrub could harm the ecological balance as well as threaten wild life like elephants.

One alien plant, called ‘Kaha Karabu’, is suspected have grown so thick in the deep south of the island, blocking traditional elephant paths that earth- moving machines have to be used to get rid of it.

Environmentalists argue that while they have been battling the spread of century-old enemies like the water hyacinth, slack implementation of laws has resulted in more such plants entering the island. Gunewardena faults the Department of Agriculture for enforcing the law strictly against agricultural weeds while being lax on ornamental plants.

“We have a long-running case where we have been trying to get a plant known as ‘Valentine’ banned, but we lack support from the agriculture authorities,” he told IPS. The plant that blooms in February—hence its name— is considered an invasive plant of the highest priority on the Hawaiian islands, but can still be brought into Sri Lanka relatively easily as an ornamental plant.

Chamikara of the SLEA aid that authorities should find ways to use invasive plants in a profitable manner. He believes that the spread could be fast and wide when it happens in the wild. “If you can promote the use of these plants as fertiliser or animal feed, the people tend to be in charge of the growth, and you can monitor the spread.”

Gunewardena told IPS that alien plants make it into the ecosystem due to the lack of public knowledge. “It is not something that you can do fast; you have to educate the public, especially children, on the harm these plants can cause. Awareness and proper implementation of laws can help stem this spread.”

Without these, there are bound to be more water hyacinth-like menaces to the environment.

 
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