Exploring South Africa’s blue urban forests
What a beautiful time of the year it is. We have finally received the first decent rainfall and we are ever hopeful that it was not the last. Looking at the Vaal Dam levels and the Category 2 water restrictions it has been hard in the landscape industry. I am sure that there are many landscapers, farmers and gardeners who are really struggling with this drought. Please share your tips on water saving with us.
As the drought perseveres I have noticed many indigenous and exotic shrubs that are not endemic to specific regions have passed their sell-by date. What is actually more astounding is how many exotic large trees there are. I am not against all exotic trees; Johannesburg is the largest manmade forest due to the rapid expansion of building developments and thus creating landscaped masterpieces, many of which plant exotic and indigenous plant species.
Some of you may argue and say that all exotics are terrible, but then I could say, so are non-endemic species. They are also foreign if planted in the wrong region. As an example: Fever tree’s (Vachellia Xanthopholea) natural distribution is near rivers and swamps from KwaZulu-Natal, through to Mpumalanga, Limpopo and up into Kenya. The Fever tree is stunning when planted in gardens but because it is not endemic to the Johannesburg region it poses just as big a threat to our underground water supply as exotic plant species.
Invasive plant species
Invasive species that have been introduced into an area are able to outcompete and displace indigenous species. They may be amphibians, birds, fish, insects, mammals, plants and reptiles, and are widely regarded among the biggest threats to the productive use of land and water, to the ecological functioning of natural eco-systems, to health and to the economy.
Did you know? The South African government and the National Environmental Biodiversity Department has introduced new laws which affects all property owners within South Africa. This new law will not only affect property owners, but will also affect the nursery, landscape and other green industries.
Invasive species are controlled by the National Environmental Management Biodiversity Act: 2004 (NEMBA) (Act no. 10 of 2004) – Alien and Invasive Species (AIS) Regulations which became law on 1 October 2014. The act and regulations set out various degrees of control methods. All invasive species need to be documented, and in some cases removed. Invasive species are divided into four categories: 1a, 1b, 2 and 3. To find out more about these categories visit Invasive Species South Africa and Invasive Species Consultants.
The Blue Forests of Southern Africa can only get this name due to the invasive species Jacaranda mimosifolia (Bignoniaceae); its alternative names include the Blue Brazilian and the Fern Tree and, in Afrikaans, the Jakaranda.
It is the best known city tree in Pretoria and Johannesburg. In the warmer areas of the Highveld the tree is semi deciduous and in the cooler climates around the rest of the country it is deciduous. The tree can grow to a height of 25m with a large open crown. The Jacaranda originates from South America and parts of Argentina, and is spread by seed dispersal. Most Jacarandas are blue, but if you are fortunate enough you will spot a white one.
The Jacaranda is a CARA 2002 – Category 3 NEMBA – 1b in Gauteng, KwaZulu-Natal, Limpopo, Mpumalanga and the North West Province. The Jacaranda is not listed within urban areas in Gauteng, KwaZulu-Natal, Limpopo, Mpumalanga and the North West Province.
Category 3 invasive species are those whose spread must be contained as these plants have the potential to become serious invasives.
The Jacaranda is not listed if it is within 50m of the main house on a farm within Gauteng, KwaZulu-Natal, Limpopo, Mpumalanga and the North West Province, and if it has a diameter of more than 400mm at 100m height at the time of publishing of this notice. Any Jacaranda within a riparian area (near the banks of a river) must be removed. The Jacaranda is not listed elsewhere, which is due to the fact that the department took public sentiment for the much loved Jacaranda into consideration when deciding on the level of control that would be required for the species, and found that it would allow the continued use of the tree as decoration and ornament in our cities.
Enjoy the blue-lined avenues of Jacarandas, and the blue flowers that make the ground look like carpet. They are beautiful at this time of year when they flower. But please remember that they are an alien species to Southern Africa.
Who is Nicholas Spargo?
Nicholas Spargo, owner of Spargo Landscape Consultants, has been in the landscape trade for 12 years as well as being a lecturer at the Lifestyle Garden Design Centre for the past year. He was awarded a Gold for a design at the Lifestyle Garden Design Centre Design Show in 2008, is an Invasive Species Consultant and is affiliated with the South African Green Industries Council.
Landscaping and education are very close to his heart.