Pretoria is known as the Jacaranda city, with the trees being integral to the image and personality of the metro. An expert at the parks division of Thswane metro gives clarity on the city’s stance on jacarandas and lays rumours to rest.

Residents and tourists flock to the streets of Pretoria for a few weeks every year to view the splendour of jacarandas in full bloom. All the hype about the trees leads to rumours and stories about their past and future, but the metro wants to set the record straight — the jacarandas are here to stay.

Jacarandas are indigenous to South America, with the first tree planted in Pretoria in 1888, and in town in 1906. As non-indigenous trees they are considered invasive species in South Africa.

In 2015, the Gauteng government condoned the jacarandas in Gauteng even though they remain on the invaders’ list. This decision was made because of the heritage and significance of the tree in the region and considering the local symbiotic relationship between the jacarandas and the vegetation that has emerged in the urban areas.

Andre Valkenburg works in urban forestry at the environmental management and parks division at the Tshwane metro and is affectionately known as Mr Jacaranda by some of his students.

A rumour that the trees would be cut down due to their status as invaders was put to rest by Valkenburg who confirmed that the city is proud of the trees, and that they are here to stay.

Valkenburg told Pretoria Rekord the metro ‘has full intentions to keep the tree as a symbol of the city, although not necessarily to plant masses of them in new neighbourhoods. The city has a strong interest in keeping the trees’.

The impact of cutting them down

Cutting down the jacarandas would simply not be a good decision, says Valkenburg. It would take years to replace these very large trees with new ones, drastically increasing surface heating in the city. It would also collapse the symbiotic relationship between the jacarandas and other plants in the city.

He says the metro grow jacarandas in a nursery to replace those that have either died or were cut down. According to Valkenburg there is a goal to plant 8 000 trees every year around the city, with many of these trees being jacarandas. This goal is quite a low target, especially compared to previous years, but the number is more in line with budgets and easier to achieve.

When it comes to strategies for managing the trees, Valkenburg says the options are cutting down, moving or replacing them with younger trees.

Trees in public areas, along roads, parks and other open spaces cannot be cut down without a permit from the city. He says if a tree is in the way of a water and sanitation pipeline that needs to be laid, the city needs to be consulted before it can be cut down or tampered with.

They always want to investigate if another option can be devised or if the tree can be relocated.

Deadly fungus their biggest threat

The biggest threat to their existence currently, is not people but a fungus, carried by a beetle, that can kill parts, or even the entire tree.

The Polyphagous Shot Hole Borer from Southeast Asia burrow into the stem of a tree carrying the fungus into the tree.

When the tree is stressed, such as in extreme heat, drought, or extreme cold, it can cause some branches to die back, and in the worst case affect the whole tree.

Pretoria lost some trees when the beetle’s presence was first noticed a few years ago. According to Valkenburg the effect is seasonal and dependent on the conditions during the year. At the moment, there is not too much to worry about, Valkenburg assures the newspaper.

He says the city has sent out specialists to treat the affected trees.

Water wise

Jacarandas have a reputation for being heavy water users as invaders. But Valkenburg says that jacarandas are quite average water consumers.

He explains that there are two schools of thought around trees and water-wise policies.

One group feels that trees indigenous to South Africa are best, while the other says plants that are endemic to the area specifically are best.

But this can often be misleading, as some trees that are indigenous to the Western Cape, for example, can be heavier water users than jacarandas, but trees like olienhout, karee, and white stinkwood, which originally grew in the Tshwane area, are perfectly suited to the climate here.

Jacarandas have become symbiotic to many other species found in the area. Very often they need to be planted after the saplings have been raised in a nursery.

The city is working on policies and strategies to formally protect the trees in their local settings.