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Cape Town – Ecologically-minded Capetonians may be up in arms when they see a helicopter flying up and down the slopes of Table Mountain while large trees are being felled one after the other, but they can take comfort in the fact that the whole operation is to protect the Western Cape’s floral kingdom from invasive alien trees.

Depending on the weather conditions, the operation – referred to as a Helihack – is scheduled for the weekend of 6 to 8 October (Helihacks are usually planned over spring or autumn weekends when skies are clear, the mountain wet and temperatures mild).

About eighteen volunteers will take part in the operation, all of them skilled mountaineers and tree surgeons who can handle chainsaws, rope access and other high-angle techniques. Some are affiliated with the Cape Town section of the Mountain Club of South Africa, many of them having been involved in mountain rescues.

Making use of the short-haul technique, they will be flown three at a time up the eastern slopes of Table Mountain above Kirstenbosch, taking with them equipment such as chainsaws, safety equipment, fuel, food, water and warm clothes.

“This is probably one of the most high-risk operations involving helicopters. It is more expensive, dangerous and challenging than other approaches to eradicating invasive alien vegetation, but it is the most efficient for hard-to-access terrain,” says Helihack founder, Aleck McKirdy.

Is it really necessary to fell the trees? Dr Glen Moncrieff of the South African Environmental Observation Network points out that alien invasive plants threaten native vegetation. “The aliens often cause fires that are very damaging, with much higher intensity and much harder to manage than fires that occur in native vegetation. The aliens also use a lot of water, thereby reducing the water available by both the indigenous plants and downstream users.”

“If the invasive pine trees (Pinus pinaster) are left to spread, they will colonise the area at quite a rapid rate and in a few decades’ time, the amount of runoff will be greatly reduced. By 2050 we will be losing thirty to forty percent of water from our catchments.”

Professor Ed February from the Department of Biological Sciences of the University of Cape Town states “Fynbos is a unique vegetation type, not found anywhere else in the world. That species diversity has led to the Fynbos Biome being declared a UNESCO World Heritage Site. The National Parks authorities have to clear the pines as their mandate is to conserve the biodiversity of the Western Cape, which is Fynbos. If we don’t cut the pines down, the whole of Table Mountain will in due course be covered in pines. Helihacking is the only way to get into these inaccessible places.”

Megan Taplin of South African National Parks says Table Mountain National Park is very excited to have the Helihack teams coming through. “The Helihack teams are able to access some of the areas to which standard teams cannot get on foot. We have several areas in the park that are completely inaccessible to our standard operating teams. Our teams usually work on the lower slopes and are able to clear them of alien vegetation. The Helihack teams are able to clear ravines and some of the higher slopes we cannot get to, which is why we are so excited.”

Megan points out that some of the areas and paths will be closed during the operation due to public safety. She says notices will be put up in the areas which should be avoided.

One of the Helihack volunteers, Willem le Roux, invites mountain lovers who want to do similar work on the lower areas of the mountain which can be reached on foot to assist with the clearing operation. “They can also join members of Friends of Table Mountain who will also be working on the lower slopes. You would be surprised what can be accomplished with a pair of pruning shears and a hand saw.”

He says the number of trees that can be felled in a day, depends on aspects such as the size of the trees and the density of the infestation. “A Helihack team can remove between 4,000 and 5,000 pines per weekend, depending on the density of the vegetation. I have, for instance, chopped down more than a thousand trees in a single day, but there have also been days in which I struggled to fell twenty.”

He points out that although the helicopter drop-off system is by far the most efficient way of clearing invasive aliens, it is also very costly. Sponsored by the Mountain Club of South Africa, several landowners and charitable trusts, the average weekend operation costs in excess of R350 000: despite the fact the whole Helihack team is volunteer-based, including the medics, equipment, and helicopter fuel.

“I am proud to say that, since 2017, more than 12 000 ha have been cleared in 21 Helihack operations in areas such as Greyton, Tsitsikamma, Milner Peak, Hex River and the Limietberg Mountains,” he says.