Scientists argue human activity threatens vital ecosystems

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Scientists have warned that human activity is increasingly threatening sensitive and vital ecosystems.

While the Western Cape is still not out of the woods after the worst drought in living memory, a wetland at the largest dam in the province is also under threat. If not saved, it could have a dire impact on nature as well as on humans.

Doctor Alanna Rebelo has been studying Palmiet valley bottom wetlands for five years. As a very special fynbos species, Palmiet is essential as a water purifier. It also produces peat or organic, nutrient rich sediment but it’s under serious threat.

Rebelo says such wetlands have declined by more than 30 percent and are becoming increasingly fragmented.

“I would say the dominant threat at this stage is gulley erosion where channels erode into these wetlands, cutting through the peat decreasing the water table with the result that the wetlands dry out and you get oxygen entering the soil, decomposition takes place and the entire wetland system eventually starts to collapse,” said Researcher at Stellenbosch University, Dr Alanna Rebelo.

The channel erosion occurs after each flood episode,stripping away dense Palmiet wetland. Human activity, such as road construction and agriculture, contribute to the rate of erosion. Downstream from this wetland is the Theewaterskloofdam, a major water source in the Western Cape.

Palmiet wetlands also serve as a natural percolator of water into aquifers. Their continued existence is vital and Rebelo says urgent steps must be taken to preserve and restore it.