EXPLAINER: What one mature tree actually does for city roads? 

And why even 100 seedlings can’t replace it.

You only realize how important a tree is when the shade disappears.

Along Quirino Avenue, commuters recently watched hundreds of mature trees cut down to make way for a new road project, triggering public outrage online. Beyond the sadness of seeing decades-old trees reduced to stumps, many Filipinos began asking a deeper question: what exactly does one mature tree really do for a city?

The answer is: far more than most people realize.

Natural air conditioner

A single mature roadside tree functions like a giant cooling system. Its canopy blocks sunlight from directly heating asphalt, sidewalks, and vehicles, while evapotranspiration releases water vapor that cools surrounding temperatures by as much as 2°C to 4°C.

In Metro Manila’s extreme heat, that shade is not just comfort — it can make roads survivable for commuters and pedestrians.

A giant air filter

That same tree also works like a living purifier.

Its leaves trap toxic particulate matter from vehicle exhaust while absorbing harmful gases such as nitrogen oxides, sulfur dioxide, and carbon monoxide. One mature tree can absorb around 22 kilograms of carbon dioxide yearly while releasing enough oxygen for two people.

In traffic-heavy roads, every large tree quietly cleans the air people breathe daily.

Free flood control

During storms, mature trees become invisible infrastructure.

Their canopies slow down rainwater before it hits the ground, reducing runoff that overwhelms drainage systems during heavy downpours. Their roots stabilize soil and help prevent erosion and pavement damage.

Cutting trees means removing one of the few natural systems helping cities absorb water.

Making roads safer

Tree-lined streets also influence driver behavior. Studies show roadside trees create a “tunnel effect” that naturally encourages vehicles to slow down. They reduce glare from sunlight and headlights while creating a safer buffer between cars and pedestrians.

Without trees, roads often become hotter, harsher, and more hostile to people.

Good for mental health too

Even stress levels are affected.

Greenery has been linked to lower anxiety and mental fatigue, especially for commuters trapped in traffic and residents surrounded by concrete. Mature trees soften the psychological exhaustion of urban life in ways people rarely notice until they are gone.

This is why critics say replacing old trees with seedlings is not an equal trade.

Under DENR guidelines, developers are often required to plant 100 seedlings for every tree removed. On paper, the number sounds impressive. In reality, newly planted seedlings cannot immediately replicate the cooling power, carbon absorption, flood protection, and massive canopy of a decades-old tree.

Worse, many seedlings never survive long enough to mature due to poor maintenance, heat, or urban conditions.

A mature tree takes decades to become truly valuable infrastructure. Once cut down, those benefits disappear overnight.

And no amount of seedlings can instantly bring back the shade that took generations to grow.