Popular but problematic: Exotic trees and plants in Randburg backyards

Randburg is home to a variety of exotic trees and plants that, while aesthetically pleasing, pose significant challenges to the local environment. From jacarandas and black wattles to blue gums and banana palms, these non-indigenous species have found their way into local gardens, often overshadowing native flora and impacting the ecosystem.

Pauline Dickson, a Bryanston-based environmentalist, highlighted the distinction between indigenous and exotic plants. “Indigenous forests are mainly the trees that are naturally native within a given country while the exotic forests are trees that are alien to a particular country or introduced from other parts of the world.” She explained that every continent and country has unique plant species that attract visitors eager to learn about local biodiversity.

Dickson emphasised the resilience of native plants. “Indigenous plant species habitually survive longer than non-indigenous species and do not need much nurturing because they are hardier and more disease resistant.”
This makes them not only more sustainable but also more beneficial for the environment.

Common exotic species in Randburg

Randburg’s backyards are often adorned with the following non-indigenous plants:

• Jacaranda
• Black wattle
• Blue gum
• Syringa
• Conifers
• Banana palms
• Lantana
• Brambles
• Bugweed
• Morning glory

While these plants can enhance the visual appeal of gardens, they come with several disadvantages. “Exotics are known for causing numerous problems due to their intolerance to South African soil, climate, and rainfall,” Dickson noted.
These plants often require more water and fertilisers and are more susceptible to pests, leading to an increased use of pesticides, which are both costly and environmentally harmful.

Dickson explained that exotic plants often arrived with early settlers who brought seeds from their homelands, planting them along travel routes to mark boundaries. However, this practice has had long-term ecological consequences. “Exotic vegetation along rivers and waterways does the opposite [of indigenous plants]. It encourages the plants to become dense and eventually the water does not run freely, creating water pools that become infested.”

The Benefits of Indigenous plants

Dickson passionately advocates for indigenous planting and named numerous benefits. “Indigenous plants require less water and fertiliser. They support local wildlife and improve soil quality.”

She explained that native plants are better suited to local climate conditions, reducing water usage. “Indigenous trees and plants are remarkably resilient to local pests. They have spent millions of years adapting to their environment,” she explained.
This natural resilience reduces the need for harmful pesticides.

Indigenous trees also play a crucial role in improving soil quality and water retention, decreasing soil runoff and reducing ocean pollution. “Trees provide shelter and food for wildlife such as birds, squirrels, and insects. Urban greening areas will help bring a lot more life to our cities.”

On the contrary, exotic plants can cause significant environmental issues. “Infestation is a nuisance due to their plague-like invasive abilities.”
Dickson warned that these plants could outgrow native species, depleting resources and sometimes leading to the death of indigenous flora.

Dickson urged residents and organisations to support Johannesburg City Parks and Zoo in removing invasive species and restoring indigenous vegetation. “We need public and corporate participation to take responsibility with the eradication of the aliens to bring the waterways and green spaces back to an indigenous environment.”

She explained that by planting indigenous species and managing exotic ones, Randburg can create healthier green spaces, enhance biodiversity, and ensure sustainable environmental practices for future generations.

Related article: Geoff Lockwood celebrates the arrival of fairy flycatcher in Delta Park