Key Takeaways
- Johannesburg’s claim to be the world’s largest man-made or urban forest is a popular notion, but lacks reliable evidence to support it.
- The city’s tree count varies widely, making global comparisons difficult, with estimates ranging from 3.2 million to over 10 million trees.
- Johannesburg is indeed one of the world’s largest urban forests, but not the largest, with other cities like Singapore, Sydney, and Vancouver ranking higher in terms of canopy cover.
- The claim of being the world’s largest man-made forest is also contested, with larger human-led projects like China’s Great Green Wall and Africa’s Great Green Wall existing elsewhere.
- The city’s trees are overwhelmingly the result of human effort, planted over more than a century, making it a notable example of urban forestry.
Introduction to Johannesburg’s Urban Forest
Johannesburg residents have long been proud of their city’s reputation as the world’s largest man-made forest. This claim is often repeated with confidence, used in tourism marketing, and cited as a unique aspect of the city’s identity. However, when tested against definitions, global examples, and independent scrutiny, the claim becomes harder to prove. The city’s tree-rich landscape is undeniable, with almost every tree planted by people, but the superlative itself is contested.
Defining Urban Forests
A forest, in ecological terms, refers to a largely contiguous area where trees dominate the landscape and form a self-sustaining ecosystem. Cities, on the other hand, have fragmented tree cover due to roads, walls, private gardens, and infrastructure. Urban planners and environmental researchers use the term "urban forest" to describe the collective tree cover in a city, including street plantings, parks, gardens, and remnant natural areas. Johannesburg clearly qualifies as having an urban forest, but calling it a literal forest is a stretch.
Tree Count Variations
The City of Johannesburg has cited varying tree counts, ranging from over six million to over 10 million trees. Johannesburg City Parks and Zoo has also provided estimates, including 3.2 million trees in public spaces and a total of around 10 million trees, with a large proportion on private property. These numbers reflect different counting methods and scopes, making it challenging to establish a single, reliable tree count. The lack of a citywide tree inventory hampers meaningful global comparisons.
Measuring Trees and Canopy Cover
Projects like the MIT Senseable City Lab’s Treepedia initiative use street-level imagery to assess canopy cover, producing a "green view index" that captures the lived experience of pedestrians. According to this methodology, Johannesburg ranks sixth in the world, behind cities like Singapore, Sydney, and Vancouver. This highlights the importance of considering different measurement methods and the uneven distribution of tree cover in the city, with wealthier areas tend to be greener than poorer ones.
Global Comparisons and Contesting Claims
Johannesburg is undeniably one of the greenest large cities in the world, given its grassland origins and semi-arid climate. However, the claim of being the world’s largest man-made forest is contested by larger human-led projects like China’s Great Green Wall and Africa’s Great Green Wall. These initiatives involve billions of planted trees and span thousands of kilometers, eclipsing Johannesburg’s urban forest in scale. Countries like Brazil, Chile, Sweden, and Finland also have vast plantation forests, planted for timber, carbon sequestration, and land rehabilitation, which are comparable to Johannesburg’s treescape.
The Enduring Claim and Its Significance
Despite the lack of reliable evidence, the claim of being the world’s largest man-made forest has stuck, occupying a narrow rhetorical niche and resonating with the city’s identity. The scale of Johannesburg’s tree cover is striking, and the city’s trees are deeply embedded in its history and culture. However, it is essential to distinguish between the claim of being the world’s largest man-made forest and the fact that Johannesburg is one of the world’s largest urban forests. The latter is a notable achievement, worthy of recognition and pride, but the former is a claim that requires more nuanced understanding and evidence.