The swamp that ‘invaders’ saved from killer grass

By Harold Ayodo

A visitor at Saiwa Swamp National Park may be surprised see locals wielding machetes and sickles cutting elephant grass and ferrying it away without fear of being detained by Kenya Wildlife Service (KWS) warders.

But they would be relieved to learn that their ‘invasion’ of the protected area is not only approved by the service but is for a good cause — protecting the park’s biodiversity that is under threat from the elephant grass — Pennisetum purpereum.

As a temporary measure to control the noxious grass that is threatening biodiversity, KWS occasionally allows residents into the conservation area to cut the weed for their livestock.

Scientists say because of climate change, the grass is growing too fast and is replacing the wetland habitat, which is mainly papyrus.

Hunt wildlife

Warden Mary Mayende says they monitor the locals to ensure they do not use they opportunity to hunt wildlife.

But as residents have a field day harvesting livestock feed, scientists are on their wits end trying to contain the deadly plant.

Researchers are restricted to using methods that do not compromise other animals and plants. For instance, burning would kill other untargeted animals.

KWS Senior Researcher Frederick Lala says climate change is causing reduction of water that flows into the swamp hampering the growth of papyrus while enabling elephant grass it thrive. "Elephant grass thrives in areas where water levels have receded like Saiwa," Lala says.

He says heavy chemical use by farmers also contributes to the unfolding disaster in the tranquil park. "Saiwa is surrounded by a farming community and remnants of chemical fertilisers flow into the wetland," Lala says.

The researcher says disadvantages of the invasive weed were first documented in the 9km long national park in 1970. "The drought tolerant elephant grass is an opportunistic weed that out competes other native vegetation that herbivorous animals like sitatunga and waterbuck rely on," Lala says.

Flagship animal

Indeed the grass is posing a threat to the endangered sitatunga – a semi-aquatic antelope, which, the park was created to conserve.

The sitatunga, the flagship animal at the park, does not feed on fully-grown coarse elephant grass. The scientist say survival of the animal is also threatened by inbreeding, which weakens the genetic pool.

Already animals like the waterbucks are extinct in the area.

Other wildlife species in the swamp include the Otter, Genet cat, Serval cat, mongoose, bushbuck, monkeys and 372 bird species.

Lala says increased deposition of silt and change of river courses are also harming the park.