Veteran warriors

Veteran warriors

Young trees take several years before they can offset pollution, writes Marianne de Nazareth batting for Bangalore’s hoary green cover
Photo: Murali Kumar K.

Leafy lane Mother nature’s air conditioner
If you take a trip up to Ooty or Coonoor even today, the air-conditioned climate in the cities is what strikes you immediately. That was Bangalore way back in the Seventies when tree cover was optimum and homes were sprawling, old, colonial bungalows . Trees grew in abundance and were of a massive girth with canopies that spread across roads and buildings. The city was famed for its ‘air-conditioned’ ambience. Today we use fans even in January and the city has warmed up to a level that makes air-conditioners essential.

In a recent Climate Change meeting of the UNFCCC in Bonn, an organization called the Global Canopy Programme (GCP) from the UK explained that “old trees go beyond carbon sequestration and storage, and act as giant utilities providing vital ecosystems services to the city. They generate rainfall, buffer the climate, maintain biodiversity and also stabilize the soil. Although we all benefit from these services, nobody pays for them.Therefore keeping them safe, keeps us safe.”

Dr J.K. Vasantkumar, the former director of horticulture, Lalbagh says, “A new tree takes 25 years to grow, whereas an old tree already has a huge canopy which not only gives shelter, but also prevents evaporation of water and soil erosion. Old trees absorb the carbon in the atmosphere and give out oxygen helping to reduce pollution in the city. A sapling is like a child, it has several years to grow before it can contribute to off-setting pollution.”

Trees act as air-conditioners, cooling the atmosphere near the ground through evapo-transpiration. According to the GCP, “one square metre of the oceans surface evaporates one square metre litre of water, old trees release eight to 19 times more moisture into the atmosphere. The Amazon forest’s trees release 20 billion tonnes of water into the atmosphere each day. The energy used by this process is equivalent to 80,000 power stations.”

The Associate Director of Research, UAS, Dr. Nutan says, “the value of a tree over 60 years old is more in terms of oxygen and micro-climate effects. This tree absorbs 3,000 kg of carbon dioxide and gives us back 2,000 kg of oxygen everyday besides regulating moisture in the atmosphere. There is also an economic value dimension of an old tree in terms of produce and seeds for propagation.”

The complex chemistry released by tropical old trees according to the GCP helps generate rainfall that stabilizes local weather patterns. And the tree root mat of an old tree is large and spreading. This plays a crucial role in holding together the substrate upon which they grow. This prevents soil erosion and loss of valuable top soil.

“A few years ago, old or mature trees were regarded as carbon-neutral. As such, they were considered irrelevant as carbon sinks and, consequently, of no importance to the climate change regime. Their relevance was solely recognised from the biodiversity viewpoint. How fortunate we are that today’s science dispelled this notion,” reveals Sergio Serra, Ambassador for Climate Change, Ministry of External Relations, Brazil

“Old trees definitely support the environment,” says Mr. Hubert, Deputy Conservator of Forest, BBMP, “But during the recent rains the fall of old trees is higher than the new trees. In Bangalore, Rain trees and Gulmohur have grown old and with the rains, huge branches fall causing massive destruction of property. Therefore trimming of avenue trees is definitely needed. After the rains people should call the BBMP control room on 2221188 and inform us about weak trees and branches. I do not disagree with the need for old trees, but this is the practical problem we face with avenue trees.”


Old trees have a huge canopy, which not only gives shelter, but also prevents evaporation of water and soil erosion.

They absorb the carbon and give out oxygen helping to reduce pollution in the city

A tree over 60 years old absorbs 3,000 kg of carbon dioxide and gives back 2,000 kg of oxygen everyday besides regulating moisture in the atmosphere.

There is also an economic value in terms of produce and seeds for propagation.