News24 | Why Johannesburg’s ‘largest man-made forest’ claim doesn’t stand up to the facts

• Johannesburg’s claim to be the world’s largest man-made or urban forest is popular, but there is no reliable evidence to support it.
• Official estimates of how many trees the city has vary widely, making meaningful global comparisons difficult.
• The evidence instead suggests Johannesburg is one of the world’s largest urban forests, but not the largest.

If there is one thing Johannesburg residents have been near-universally proud of, and unusually determined about, it is the claim that they live in the world’s largest man-made forest.

It is repeated with confidence at dinner tables, woven into tourism marketing, and used frequently to explain the city’s striking greenness.

Fly into the city on a clear summer’s day, or round one of its undulating hills, and the canopy of dense green, dotted through suburbs, parks, and golf courses, is undeniably impressive.

Sometimes “man-made forest” falls away for “largest urban forest”, as if the two phrases are interchangeable, which they are not. And once the claim is tested against definitions, global examples, numbers and independent scrutiny, it becomes clear that while Johannesburg is genuinely tree-rich, the superlative itself is far harder to prove.

This isn’t to say the achievement isn’t impressive.

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Unlike cities like Cape Town or Durban, Johannesburg was not built around a river, ocean, or a natural forest. The Highveld it rose from was largely open grassland, and so, remarkably, almost every tree that defines the city today was planted by people.

That much is not in dispute, but what it adds up to is contested.

A forest, an urban forest, or something else entirely?

A forest, in ecological terms, usually refers to a largely contiguous area where trees dominate the landscape and form a self-sustaining ecosystem.

Cities do not work like that, with their trees fragmented by roads, walls, private gardens, pavements and infrastructure.

Urban planners and environmental researchers, therefore, use the term “urban forest”. According to the Food and Agriculture Organisation, urban forestry includes all trees in a city, from street plantings and parks to gardens and remnant natural areas. It is a deliberately broad category, designed to capture how trees function in human settlements rather than how they behave in the wild.

Under that definition, Johannesburg clearly qualifies as having an urban forest. Calling it a literal forest is a stretch, but the two are often blurred in casual conversation.

How many trees are there, actually?

To back up the claim of the world’s largest urban forest, a tree count or an accurate estimate would be necessary. But ask how many trees Johannesburg has, and the answers vary, sometimes dramatically, even when they come from official sources.

The City of Johannesburg has at different times cited figures ranging from more than six million trees to more than 10 million.

Johannesburg City Parks and Zoo has cited totals of 3.2 million in public spaces, and a total in the region of 10 million, typically noting that a large proportion are on private property rather than in public parks or along streets.

All of these numbers can be cited in good faith, and they aren’t necessarily contradictory. Instead, they often reflect different counting methods and scopes, with some estimates attempting to include every tree in every garden, while others count only trees managed by the city.

But none are based on a single, publicly available, citywide tree inventory that would allow Johannesburg to be cleanly compared to other global cities.

That uncertainty alone makes a definitive “largest in the world” ranking difficult to sustain, although some organisations have tried – and have shown that Joburg is somewhat lower than many believe.

Measuring trees in different ways

One reason the claim persists and is contested is that trees can be measured in more than one way, including by counting individual trunks or by evaluating canopy cover.

Projects such as the MIT Senseable City Lab’s Treepedia initiative use street-level imagery to assess how much greenery pedestrians actually see.

This produces a “green view index” in a percentage form rather than a tree count.

It captures lived experience, but not total volume, which means large parks and private gardens may be underrepresented, while leafy streets score highly.

Still, according to this methodology, Johannesburg ranks sixth in the world, below Singapore, Sydney, Vancouver, Cambridge, and even fellow South African city Durban.

Johannesburg performs well in its established northern suburbs, but it does not dominate global rankings as many claim.

More importantly, these tools highlight a less comfortable truth that tree cover in the city is uneven. Wealthier areas tend to be significantly greener than poorer ones, a pattern shaped by history, apartheid spatial planning, and ongoing investment.

Does the claim hold?

Johannesburg is undeniably one of the greenest large cities in the world, especially given its grassland origins and semi-arid climate.

Its trees are overwhelmingly the result of human effort, planted over more than a century. In that sense, the pride is understandable. But the city is not unique in having a large, deliberately planted treescape. This is a key reason the “largest man-made forest” claim does not withstand scrutiny.

Around the world, far larger human-led projects exist, even if they are not urban.

China’s Three-North Shelterbelt, often called the Great Green Wall, has been under construction since 1978 and stretches across northern China.

It spans thousands of kilometres, involves billions of planted trees, and is widely regarded as one of the largest ecological engineering projects ever attempted.

By any conventional measure of scale, it alone eclipses Johannesburg’s urban or man-made forest.

Similarly, Africa’s Great Green Wall is a continental-scale effort running from Senegal to Djibouti, aiming to restore tens of millions of hectares of degraded land.

Beyond these headline initiatives, countries such as Brazil, Chile, Sweden and Finland contain vast plantation forests planted for timber, carbon sequestration and land rehabilitation.

These landscapes are undeniably human-made and comparable to Johannesburg’s treescape, even if they aren’t described in quite as symbolic terms.

A catchy phrase

Increasingly, official sources have started to deviate from the claim, while some use it somewhat mischievously.

South African Tourism’s website states that Joburg “is now the biggest urban forest in the world, with over 10 million trees in its city, gardens, 600 parks, open spaces and suburbs”.

The claim has stuck largely because it occupies a narrow rhetorical niche, and because it is unusual for a major city built on former grassland to be so leafy. The scale is striking from the air, pleasant on the ground in those suburbs lucky enough to have them, and trees are deeply embedded in the city’s identity.

But that is a different claim from being undeniably the world’s largest planted, urban, or man-made forest. There is no reliable source to back this claim. Instead, Johannesburg is therefore more accurately described as one of the world’s largest urban forests, not the largest man-made forest in any global sense.

*At News24, facts matter. This article was produced by the News24 Fact Check Desk and supported by Truth First. If there is something you’d like us to check out, debunk or uncover, send an email to our desk at debunk@news24.com.