Watercourse restoration in critically endangered Renosterveld

Photo Credit: Renosterveld Overberg Trust

Background

A portrait of the Western Cape 300 years ago would show rolling expanses of a vegetation type with an extraordinary diversity of bulb species called Renosterveld being grazed by large numbers of big game, including the extinct bluebuck, the quagga, as well as eland and black rhino. Today the large numbers of game have gone and the Renosterveld is down to 5% of its original expanse, with less than 50 remaining fragments in the Overberg that are over 100 ha, and even fewer of this size in the Swartberg. An emergency response is required to prevent the extinction of this jewel in the Cape Floristic Region: the smallest and richest plant kingdom on earth. The emergency response starts with restoring the watercourses that link and feed these fragments, which are the only source of intact biodiversity in the region’s farming landscape. This is what the WWF Nedbank Green Trust is funding through the project titled Watercourse Restoration in Critically Endangered Renosterveld.

Renosterveld is one of the richest ecosystems in the world, mostly due to its extraordinary bulb diversity. However, 95% of it has been replaced by large-scale commercial agriculture, mainly wheat, barley and canola, which are rotated with oats and lucerne. In its original state Renosterveld was probably a far more grassy system, with a higher rooigras (Themeda triandra) component, and significantly higher plant diversity. The combination of free-range grazing and browsing game maintained the diversity and structure of this system. As agriculture encroached on this land, the historic disregard for Renosterveld was emphasised in its description as ‘uitvalgrond’ or ‘wasteland’.

We have now identified ecological corridors in the form of streams, rivers and seepage areas that link the disparate patches of Renosterveld between farms in the Overberg Rûens (wheat belt). These watercourses are the lifeblood of this habitat and support the ecological integrity of the entire region, but many of them are in a badly degraded state. Numerous rivers, streams and wetlands have been invaded by alien invasive vegetation, or are suffering from advanced soil erosion and water pollution or destruction by ploughing. Restoring these watercourses and assisting landowners with managing them paves the way for water conservation, ecosystem restoration and better land management in this fragile system. Partnering with farmers and landowners is the only way in which we can restore the health of these watercourses and prevent this unique habitat from an otherwise inevitable extinction. What is so encouraging is how many farmers are interested and on board, and have come to us for advice and help since the project began.

We are currently working with about 50 farmers, many of whom have been invited to sign a conservation easement or memorandum of understanding with the Overberg Renosterveld Conservation Trust. The former is a conservation servitude on their title deed, while the latter is ‘gentleman’s agreement’ in the form of a written commitment for the farmers to manage the watercourses and Renosterveld habitat on their land. Both agreements are tied to a conservation and biodiversity management plan.

To encourage the farmers to work with us, we assist them with various management interventions (as identified in their management plan). These include undertaking controlled burns at the right time of the year, fencing remnants and watercourses to enable livestock management, clearing woody aliens in watercourses, and undertaking erosion-control measures to slow down and reverse the damage caused by sleet and gully erosion. We also provide landowners with a full-colour report of the Renosterveld habitat on their land. Through this initiative many farmers have stopped ploughing up the Renosterveld remnants and watercourses, and there is encouraging commitment to biodiversity conservation to improve the health and ecological integrity of this region. An exciting recent project find has been the discovery of two indigenous fish species – the Cape kurper (Sanelia capensis) and Burchell’s redfin (Pseudobarbus burchelli) in the Hansjes River near the village of Napier. It was previously thought that redfins do not occur in the Renosterveld system. Many mammals that are rare in this landscape, including Cape clawless otter, honey badger, aardwolf, several antelope and small predators such as mongoose, are completely dependent on the refuges created by these remnants and watercourses, as revealed by our camera traps. The long-term persistence of many species is entirely reliant on the maintenance of these severely threatened habitats.

For more information visit http://overbergrenosterveld.org.za/watercourse-restoration-project/.

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