“Is Johannesburg, seriously, the largest man-made forest in the world?” It is a question Talk Radio 702 host Jenny Crwys-Williams put to Africa Check's Southern Africa Editor, Julian Rademeyer, during his appearance on her show this month. And it is a question that was uppermost in the minds of many listeners.
“I mean, we say we are a world-class African city. There is absolutely no way of quantifying that. But are we genuinely the largest man-made forest in the world, because other countries have got very leafy cities. I’m just wondering about that.”
The claim that Johannesburg is the "largest man-made forest" in the world is a claim that many Johannesburg residents have come to accept as fact. It is a subject of dinner table conversation of the "did you know" variety. Numerous websites like this one make the claim, and when they do, they often can quote Johannesburg city officials backing it up. Theresa van der Merwe, for example, from the committee for community development at the City of Johannesburg, said in 2011 that Johannesburg is “well known for being the most densely treed man-made forest in the world”.
This might be well known, but is it an urban myth?
“I don’t want it to be not true,” Crwys-Williams said.
What is the evidence?
One of the callers to the radio show, who was identified as "Mike from Hoedspruit", offered what he said was proof.
Mike said he had served on the board of Trees & Food South Africa and added: “It was often spoken about, it being the largest man-made forest in the world."
"It is true,” he said. “Look at photographs from 1910 or whenever and compare it to today. You might say Rio’s got more trees but we are talking man-made forest." There you are. "Authenticated!”
Do Johannesburg's trees make it a forest?
The first question is whether Johannesburg's many trees do in fact make it a forest. If we take the Oxford English Dictionary definition as a starting point, this looks doubtful.
A forest, it says, is “a large area covered chiefly with trees and undergrowth”. Does that describe Johannesburg? According to the official City of Johannesburg website, the city is home to 6 million trees and looks like a “rain forest” on satellite pictures. Really? Well, not exactly.
The photo on the right is a satellite image of central Johannesburg in 2010. And from what it and other satellite images of the city show, it is clear that at the very least a significant part of Johannesburg is covered by roads, buildings, parks and other open spaces that are definitely not forest material.
So, even if some experts put the number of trees in the city higher than suggested by the City of Johannesburg website, it is still a stretch to call it a forest because trees would not appear to be the chief feature.
Alan Buff, from Johannesburg City Parks, told Africa Check that after the various constituent municipalities were combined to form one “unicity”, a tree census was done and found that “there are well in excess of 10 million” trees in the greater Johannesburg area.
However this did not make it a forest, he said. And, even if you use the looser term "urban forest" - meaning a densely-wooded urban area - Johannesburg is still probably “only one of the largest man-made urban forests in the world,” he said.
It is certainly man-made
What is certain is that the "urban forest" such as it is today is man, or man-and-woman-made.
Historically the area where Johannesburg is now situated was grassland. The trees its residents enjoy today are, for the most part, not indigenous. They were brought in and planted. Today, according to the City of Johannesburg website, there are 1.2 million trees within parks and on pavements and an estimated 4.8 million trees in private gardens.
But, as Buff pointed out, many other cities are also densely covered in trees and many of these plantings were carried out deliberately too. New York City, for instance, has 5.2 million trees and plans to plant another million by 2017.
One rival routinely suggested for the title of the world's largest urban forest is the Tijuca Forest in Rio de Janeiro, Brazil, which exists today because hundreds of thousands of seedlings were planted by hand in the 19th and early 20th centuries in an area stripped almost bare by its earlier inhabitants. While it has far fewer trees than Johannesburg, it is a forest in the strict sense of the word and reportedly covers a 39-square-kilometre area.
Another contender for the title is the Nebraska National Forest in the United States which has at various times been described as the "largest man-made forest in the Western Hempishere", the "largest man-made forest in the world", and the "largest hand-planted forest" in the world.
China's tree-planting scheme
Such efforts appear dwarfed, however, by those being attempted in recent years by China which is growing a "Green Wall" of forest in a bid to keep the shifting sands of the Gobi desert at bay.
As set out in this 2010 report from the UK's Guardian newspaper, a man-made forest in China today covers more than 500,000 square kilometres, well over 50 times the size of the greater metropolitan area of Johannesburg.
“Ordinary citizens have planted some 56 billion trees across China in the last decade, according to government statistics,” the report states.
Known as the "Great Green Wall," the man-made forest, designed to stop desertification and fight climate change, is meant to eventually cover more than 42 percent of China's landmass. Former United States Vice President Al Gore called the initiative "the largest tree-planting programme the world has ever seen."
A recent BBC report stated that by 2050 China planned to plant 14 million hectares of forest. But it is a controversial project with scientists questioning how effective the giant reforestation exercise will be in stopping the encroaching desert. Some have charged that it is an "expensive band-aid on a centuries old wound".
Conclusion: Not the largest man-made forest but they are great trees
We think it is reasonable to question some of the numbers claimed by Chinese officials, but, even if they are out by a few billion trees, it is clear that the Chinese forestation programme is greater than any seen elsewhere.
A flashing red warning should come attached to any claim to be "the largest" or "tallest" or "best" in the world, save where the evidence is clear. In this instance, there are no credible rankings for the largest man-made forest in the world or the largest urban forest or even the most forested city. The claim is unsupported by evidence and is indeed an urban myth.
That is no reason to feel put out. The trees of Johannesburg do not constitute a forest, in the proper sense of the term. And Johannesburg may not be the largest man-made area of woodland in the world. But the city trees are a precious asset and help make the city what it is. With its millions of trees, Johannesburg can indeed claim to be one of the most wooded cities in the world.