Environment & Social

Weeding Out Invader

Weeding Out Invader


“Mimosa spreads so quickly that unless checked it becomes a real obstacle to people’s lives.” Phouthakone Luangyotha, NTPC Biodiversity Officer. 

On a hot May afternoon on the Nakai Plateau in central Laos, two women and two men wade through thick bush at the side of a country road, pausing at certain shrubs to splice the thick stems with a knife and pour herbicide into the wounds. Safely clad in gloves, masks and helmets, they examine the thorny branches of this weed for seed pods, stripping any they find and placing the pods in a sealed box. Later the bushes’ potential offspring will be carefully destroyed.

This uncompromising treatment of the plants is carefully planned in a bid to control Mimosa pigra, also known as the giant sensitive tree. The plant, originally from South America, is a ferocious competitor for soil nutrients and space and has spread rapidly across parts of Southeast Asia. On the Nakai Plateau, where poor spoils and limited space are being carefully managed to build sustainable livelihoods for people resettled as part of the Nam Theun 2 Multi-Purpose Project, its presence is most unwelcome.

Ms Daovy of the Nakai District Environmental Management Unit is one of the team working to remove such invasive species from the plateau. Aside from Mimosa, two other species are targetted, water hyacinth and water lettuce, both of which could affect the reservoir and other local waterways. “These plants reduce biological diversity by eliminating native plants”, explains Daovy, “and they also block access to land and waterways both for local people and animals”.

NTPC has trained and equipped Daovy and her colleagues from the local agriculture     and forestry office to spot, record and destroy such plants. In turn she works with people from resettlement villages, encouraging them to report sightings and destroy invasive plants when they can. In the case of Mimosa, which has thick brances and long thorns, this is often not possible and the job of killing the shrubs is left to the professionals.

“It’s a tough but necessary job,” says Daovy. “If we don’t get act quickly these plants will spread and be unmanageable. Thanks to NTPC we have good training and equipment, and now we need to get all the local farmers aware of the issue. If everyone contributes, we can protect the environment from invasive species”.