South Africa’s wetlands are the most threatened ecosystem in the country, the National Biodiversity Assessment 2011 (NBA 2011) has found.

KwaZulu-Natal, North West and Gauteng were expected to have no natural vegetation outside of protected areas by 2050.

Environmental Affairs Minister Edna Molewa released the NBA 2011 in the northern KwaZulu-Natal town of St Lucia on Tuesday.

Based on NBA 2011, the growth of agriculture, mining and urban sprawl were the main causes of a loss of natural vegetation in the three provinces, according to the presentation.

Areas taken over by non-native or alien invasive plants had more than doubled from 10 million hectares to 20 million hectares between the mid-1990s and 2007.

"Failure to protect biodiversity is self-defeating because we are all going to lose in the end, the rural poor being the most affected. This is because many of our communities are directly dependent on biodiversity and ecosystems services," said Molewa.

She said that while many people were aware of the need for roads and electricity, not enough realised "the services we get from our ecological infrastructure like wetlands, mountains, rivers, coastal dunes and vegetation".

"These ecosystem services, like municipal services, play an essential role in supporting social development and economic prosperity."

NBA 2011 is a comprehensive technical assessment of the state of South Africa’s biodiversity and ecosystems, across terrestrial, freshwater, estuarine and marine environments.