Deepa is a freelance researcher and journalist. She writes and makes documentaries and videos.
The Tree of Our Life
There is a huge mango tree in the backyard of our ancestral home. It shades an entire side of our house and during the monsoon months, our upstairs room windows open to the rain, dancing on its canopy. The leaves dance along. Come summer, the very same thick leaves carry cool breezes to our windows. Without air conditioning and fans, we would survive summer all the way. Autumn brings to bloom the sweet mangoes which we and all our neighbors eat to our fill. Ripe mangoes are put in curries, pickled, eaten as dessert and sun-dried or slow-heated to be preserved as puree. Winter will pull down all the dried and old branches from the tree and that would meet the limited firewood needs of our otherwise LPG-driven semi-modern kitchen. Once a group of people came by from a fishermen's village, 12 kilometres away. They wanted to know if we would sell the mango tree as its huge trunk was suitable for them to make a traditional boat. They offered a great bargain, but naturally, we refused. We could not even imagine our life there without that Granma mango tree.
Evolution of Trees
Trees are found to have evolved about 350 million years ago. This happened in the Middle-Late Devonian geologic period. Plants were learning to live on land, and away from water, and they were gaining in diversity. Competition for sunlight made plants grow taller and evolve into trees. Gilboa was one of the first trees that appeared on earth. New York is supposed to be the place where the oldest forest on the planet stood and in a quarry in Gilboa, New York, fossils of ancient trees were discovered in the 1920s. These tree fossils came to be known as the Gilboa fossil forest and these fossils are about 385 million years old. These trees did not have woody trunks.
Plants developed on earth 470 million years ago
They gradually turned the then barren earth into a storehouse of nutrients via photosynthesis.
We owe the organic component of soil to the trees.
The physiological change that enabled trees to grow tall was their vascular system. This helped to move water from the bottom of the plant to the top.
Early trees reproduced by way of spores.
Archaeopteris that evolved 370 million years ago, were the first tall plants in the chain of evolution, they stood between ferns and pines. They could grow up to 30 meters in height.
Plants with seeds evolved 380 million years ago.
Hardy wooden trunks developed 360 million years ago.
Gymnosperms, the kind of trees that produce seeds without a fruit, also came into existence 360 million years ago. Examples are pines, junipers, cycads etc.
First flowering trees evolved 125 million years ago
Believe in a Tree
Much to our chagrin, we live on a planet that gets hotter day by day. It is time we reinvent our love for trees for the shade they provide and the natural cooling of urban landscapes they offer. In many countries, the urban policies have in them, trees, as an integral part. One simple way to start believing in trees is through a simple experiment- measure the temperature beneath the canopy of a tree and then measure the ambient temperature outside it. Inevitably both the temperatures will be different by at least 5 degrees, the tree shade being the cooler place. A tree is a micro-climate, an ecosystem, an architectural entity, that represents life, harmony and ecological balance. Even the architecture of a tree is all about that balance, which I will be explaining shortly.
Natural Air Conditioning
There are two ways in which trees reduce the temperature below and near them. One is by absorbing the radiant heat that falls above it from the sun and the second is by cooling via evaporation. Evaporative cooling is when the surfaces of the leaves cool down as they create energy using sunlight. Thicker the tree canopy, the larger the evaporation surface area and the greater the cooling effect of a tree. If your indoor plant has a large leaf surface area, it will have a cooling effect inside your room. The secret rests in the large surface area available for evaporation. In the process of cooking food using the sun’s energy, the trees also absorb carbon dioxide from the atmosphere and turn it into carbohydrates, the major food source of all living things, thereby reducing the global warming effect of this greenhouse gas. One estimate suggests that if we stop cutting down trees, we could reduce carbon emissions by 10%.
The moisture that escapes from the surface area of the leaves and the chemicals released into the atmosphere from the trees as certain smells combine to form minuscule particles termed aerosols. The aerosols turn into a hazy film that reflects sunlight and keeps the atmosphere cool. The aerosols are also known to function as ‘cloud seeds’ which help cloud formation at a lower level of the atmosphere. These clouds can reflect sunlight and cool the planet.
The Urban Heat Island
The heating phenomenon that occurs in urban spaces is called the urban heat island effect. Building materials such as concrete, steel, and glass reflect heat at high degrees. The concrete jungles, as they are called with a literary flourish, turn out to be huge furnaces that absorb sunlight and produce heat in excessive quantities. This is when the urban people begin to use air conditioners to cope with heat but these cooling gadgets create more heat and add to the oven effect.
The only lasting solution to the urban heat island effect is trees. According to the United States Environmental Protection Agency, surfaces shaded by trees are 11–25°C cooler than the surfaces that lack such shade. Trees reduce the need for air conditioning and thus help reduce energy use. As any school student would tell us, they give out oxygen and improve the quality of air. They can also to some extent protect us from heavy rain and storms. The canopy of a tree reduces the force by which rain falls on the pavements and thus helps keep them intact for a greater period. Trees also have a peaceful impact on human mental state and a cultural impact that aesthetically motivates us.
Why Live Near Trees?
Planting trees and managing them is far less expensive than buying an air conditioner. In the southern Indian state of Tamil Nadu, the government carried out extensive planting of tamarind trees on both sides of the state highways over a few decades and now they provide shade to the people along with income to the government. The tamarind fruits borne by these trees are auctioned every year for a significant amount of money. Last but not least, those tamarind lined highways that Crisscross the great plains of this vast South Indian state, are a pleasure to travel even on hot summer days.
The Singapore Experiment
Singapore, also known as the garden city, uses trees and foliage to keep it cool as a matter of policy and practice. The latest ongoing project undertaken by the government of Singapore is the One Million Trees movement, which works toward restoring nature to the urban spaces. Singapore Green Plan 2030 is a surprisingly creative plan to fill the country with greenery. It hosts the FamilyTrees program that allows families to plant a tree when a child is born. There are also Super Trees at Garden by the Bay, which are mammoth artificial tree-like structures covered in green foliage. They are solar-powered, act as air venting ducts for the close-by natural conservatories, and also collect rainwater. There is also a sprawling flower dome of 1.2 Ha and a 0.8 Ha cloud dome that displays and conserves plants from different climate zones including the tropical and the Mediterranean. Wilkinson Eyre and Grant Associates are the architects behind this project and they won international acclaim for it.
Rain trees, Angsana, Yellow Flame, Senegal Mahogany and many such species line every road and walkway of Singapore. There is also the practice of naming a tree species as a heritage tree based on the botanical, social, cultural and historical importance that it carries for the country, as well as if its girth is more than 5 meters.
As the pressure mounts on the world to go green and mitigate climate change, companies also tend to move towards green products and production modes. However, many companies also try to create a fake impression that their products and production methods are environmentally sustainable while they are not. This is what is called greenwashing. Governments also try a different kind of greenwashing when they are put under the scanner for the deforestation happening in the countries under their rule.
Tree planting drives undertaken by different governments and corporate companies often end up as a scam. The world has lost around 420 million hectares of forest in the last three decades. A 2021 study published in Nature pointed to how large-scale tree planting programs have failed to have an impact on climate change and people’s livelihood. This study was based on the tree-planting programs carried out in north India and revealed how the saplings ended up not contributing to the forest cover and replacing the broadleaf varieties of trees that supported the livelihoods of the local people.
The Architecture of Trees
In almost all the trees, the leaves spiral around the branches and the branches spiral around the trunk. Why? The first and simplest answer is that this structure helps the tree gather maximum sunlight. There is also some mathematical order in the arrangement of these spirals- 1/2, 1/3, 2/5, 3/8…and so on. If one lists the different spiral types by ascending numerical order and then adds the nominators and the denominators of the two close-by spirals, one gets the next spiral type. Once again this reminds us that nature is all about mathematics. It was the Greeks who discovered that the tree rings (rings visible on the horizontal cross-section of a tree trunk) indicate the number of years a tree has lived. All the trees living at the same age exhibit similar types and numbers of tree rings. Thus, they preserve a lot of information about that age. For example, scientists could read from the tree rings that between 536 and 541 CE, there was an extremely cold climate causing all the trees of that time to get stunted.
Trees and The Sacred
Sacred groves and trees of life, line the spiritual path that humans have traversed since time immemorial. The Ash tree of Nordic mythology, the Tree of Life in Egyptian spiritual tales, the Sidarat-al-Muntaha (Tree of Life) of Arab culture, and the sacred groves of the Hindu culture in India are a few to cite, not to mention the Biblical Garden of Eden. For humanity, to plant and conserve trees is to be on the good side of nature and to make our lives more livable too.
The Methuselah Tree
The Oldest Tree of The World
Till recently, the 5000-year old bristlecone pine tree of the White Mountains in California was thought of as the oldest tree in the world. It is named Methuselah. A Patagonian Cyprus tree in Chile’s Alerco Costero National Park has now been proven older than Methuselah. The age of the Chilean Cyprus is calculated as 5484 years and its trunk is more than 4 meters thick. Both trees look ancient and grandmotherly. How these trees survived the axe for so long is nothing less than a miracle.
The Largest Tree, The Tallest Tree
The largest tree to be known on this planet is a giant sequoia in the Sequoia National Park in California. The tree’s volume is 52,500 cubic feet and it is 2000 years old. Named General Sherman, this sequoia is 274.9 feet tall. It is named after the American Civil War General William Tecumseh Sherman, who is considered one of the architects of modern warfare. The tallest tree in the world is a Californian redwood named, Hyperion. It is 379.1 feet tall.
The Largest Tree By Volume
Limited Effects of Tree Planting on Forest Canopy Cover and Rural Livelihoods in Northern India, Nature, Volume 4, November 2021.
Whispers from the Woods, 2006, by Sandra Kynes.
Planting Trees Doesn’t Always Help with Climate Change, 26 May 2020, Michael Marshall, bbc.com.
Ancient Cyprus in Chile May Be The World’s Oldest Tree, New Study Suggests, John Bartlett, The Guardian, 2022.
The Methuselah Tree And The Secrets of Earth’s Oldest Organisms, Robin McKie, The Guardian, 2020.
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
© 2022 Deepa