Fighting aliens and finding national treasures

A PIONEERING alien vegetation clearing project at Vergelegen wine estate in Somerset West has found a national treasure of indigenous vegetation.

Some 15 hectares of critically endangered Lourensford alluvium fynbos and 105ha of critically endangered Swartland shale renosterveld, have been uncovered to date on the farm.

The International Union for Conservation of Nature categorises this vegetation as facing an extremely high risk of extinction in the wild.

The Vergelegen project is believed to be the largest private conservation programme in South Africa. It was initiated by estate owners Anglo American after a wildfire two decades ago and should be completed by the end of October this year.

Only about 60ha of alien vegetation still need to be cleared, which will bring the total of restored vegetation to some 2 200ha.

In the Western Cape, Lourensford alluvium fynbos originally extended over 6 000ha, but only 9% remains.

Some 3% of the original area is protected in the Helderberg and Harmony Flats nature reserves, with the remainder in the Lourens River area.

Some 21 known Red Data plant species occur within this vegetation type.

The Red List of South African Plants provides up to date information on the national conservation status of South Africa’s indigenous plants.

According to a specialist botanical consultant, the Lourensford alluvium fynbos on Vergelegen constitutes probably the only realistic chance to conserve a significant portion of this vegetation type.

It consists of low-lying plains, supporting low to medium dense shrubland, with an underlying layer of short, grass-like herbaceous plants.

Restios and asteraceous fynbos are dominant.

The Swartland shale renosterveld originally extended over 495 000ha in the Western Cape, but only 8% of this remains.

Less than 1% of the original area is currently protected. Some 151 known Red Data plant species occur within this vegetation type, with at least 35 endemic plant species.

This vegetation type consists of moderately undulating plains and valleys, supporting low to moderately tall shrubland, with long slender leaves of varying canopy cover, as well as low, open shrubland dominated by renosterbos.

When this Vergelegen renosterveld area was surveyed previously, eight Red Data Book species and roughly 100 different plant species were identified.

The renosterveld on the farm’s Schaapenberg area is a major regional conservation priority.

Vergelegen managing director Don Tooth says the final stretch of alien vegetation to be cleared lies in high, difficult-to-reach terrain. The clearing team will have to tackle this in harsh winter weather.

They will also undertake carefully controlled stack burns to dispose of large amounts of biomass from prior clearing, as these pose a fire hazard.

All initial clearing is done by contract teams, with two teams of 35 and 40 people respectively employed.

“After clearing has taken place, it is extremely difficult to determine the size of the seed bank of invasive aliens.

“Any wildfire will result in this dormant seedbank germinating, so it is vital that the maintenance programme deals with any re-emerging invasive aliens before seeds are produced,” Tooth says.

The estate is working closely with CapeNature, which will potentially re-introduce rare geometric tortoises into the area.

“This has been a massive undertaking, made possible by dozens of people working as a team.

“We’ve met visionary conservationists, fascinating scientists and hard-working individuals from the local community, who have created viable small enterprises through the clearing operations,” Tooth says.

Vergelegen conducts monthly bird counts, identifies wild flowers and (using infra-red camera systems) monitors wildlife movement. Species such as the Cape leopard, caracal, grey rhebok and spotted genet are regularly viewed.

On the estate, the number of bird species has soared from 80 to at least 142 and at least 500 different plant species have been recorded. – Staff Writer