The secret life of city trees and why they’re dying decades ago india news

In India’s growing cities, trees that used to live for generations are dying at an early age. Vast areas of our streets, school grounds and shady old neighborhoods are showing signs of stress that were rare just a decade ago.

Leaves turn yellow quickly, stems become weak, branches fall during light rains and many trees fail to survive for a few decades. Scientists are beginning to understand why this is so.

A research review published in May 2025 pooled together global evidence and found that air pollution is silently shortening the lives of urban trees. This trend is worrying and could change how cities like Bengaluru, Chennai and Hyderabad plan their green future.

What did the 2025 study reveal?

In May 2025, three researchers from Mexico examined dozens of global studies examining how pollution affects trees in cities. Their review showed a clear pattern. Trees growing in polluted air breathe in more particles, absorb more ozone and face constant chemical attack on their leaves and roots.

Over time, this repeated stress causes them to age faster. A twenty to thirty percent reduction in lifespan is not only possible but visible in many polluted cities around the world.

This does not mean that every tree in every Indian city will die thirty percent earlier. But it does mean that the risk is real. Trees in polluted areas consistently show reduced photosynthesis, poor growth and high mortality. When the same stress is repeated year after year, lifespan naturally becomes shorter.

How does pollution harm a living tree?

Imagine a tree trying to breathe in a city filled with dust, exhaust and industrial smoke. Each leaf has tiny pores that allow the tree to exchange gases with the atmosphere.

But in polluted cities these holes get clogged with soot, dust and fine particles. Once the pores become clogged, the leaf ceases to take up carbon dioxide. Without it, photosynthesis reduces and the tree becomes weak.

Ozone adds another layer of trouble. High ozone levels damage the inside of leaf cells. Scientists describe it as a slow burn that prevents premature aging. This invisible stress leaves branches brittle, slow to recover from storms and susceptible to pests.

The soil around the roots is also affected. Pollutants settle in the soil and change its chemistry. Heavy metals accumulate and reduce the roots’ ability to take up nutrients. Over the years, the roots become shallow, weak and unstable. Even a light wind or heavy rain can topple such a tree.

Urban trees also face heat stress, limited soil space, concrete around their roots, and chronic water scarcity. Pollution adds another burden to these existing conflicts. This combination shortens the life of a tree that would otherwise stand strong for decades.

indian angle

Although the 2025 review was global, India is not far behind in its comments. The Indian Agricultural Research Institute in Delhi has studied how common tree species respond to pollution.

Their findings echo global patterns. Trees near busy roads and industrial clusters show lower chlorophyll levels and more stress indicators compared to the same species grown in clean areas.

A study conducted in and around Mettupalayam in Tamil Nadu found that many urban species have a low tolerance for pollution, especially in areas with high vehicular traffic or dust from construction.

Bengaluru, Chennai and Hyderabad, which face rising levels of particulate matter every winter and summer, may already be seeing early signs of declining tree life. Many old avenue trees that once could live up to a century are now struggling to reach half that age.

For South India, where cities are expanding rapidly, there is concern. Sweltering heat, dust from constant construction, increased traffic and fewer rainy days mean trees are fighting several battles at once.

Why does this matter for urban life?

Urban trees aren’t just ornamental. They reduce heat, slow down rainwater runoff, support birds, filter the air and improve mental health. When they die at younger ages, cities lose these benefits faster than expected. Replacing a mature tree is not easy.

It takes decades for a plant to grow into full canopy. If trees begin to die at the age of forty instead of sixty, the city loses twenty years of shade, coolness and oxygen supply.

The impact is also felt on the municipal budget. More tree deaths means more removal, more planting and more maintenance. Heat islands become more intense. Floods become common. And air quality deteriorates as the number of living leaves that trap dust continues to decline.

what cities need to do

The message of the 2025 Review is simple. Cities need to take tree health as seriously as they do road repairs or water supplies. Trees need room for roots, regular loosening of the soil, watering during heat waves, and careful pruning.

Species that can better tolerate pollution should be selected for busy corridors. Planting trees should not be hasty or symbolic. A tree planted in a cement pit without any root space is not an investment. This is a short term decoration.

Reducing pollution even a little helps trees recover. When pollution reduces, the leaves rebuild their chlorophyll, the roots become stronger again and overall resilience improves. Saving trees starts with improving air.