70 % global population will go Urban in 2050. Urban forestry will relieve the stress for humans, but what about Stress for Trees? Urban forestry is, in simple terms, creation and management of trees in urban settings. Urban setting is changing fast, mainly because of unprecedented migration of people from rural fields to urban space. Globally, more people live in urban area than in rural area and by 2050, when the world population would reach about 9.7 billion (as per UN report), nearly 70 percent of it would be in urban setting.
The objective of urban forestry has been improving urban environment for the benefit of these urban humans. Human beings always strive hard and seek to remain cool, stress-free and lead confortable life in crowded space. And if all these aspirations can be achieved, at least partly, just by planting trees, why not?
Have we ever thought, however, what kind of stress the trees will go through when planted in urban surrounding?
Not much research is easily available on the subject. Number of arborists, environmental policy makers, green-city-architects, researchers and community activists are busy in promoting urban forests.
Urban forestry is infrastructure-driven, human-centered utility. Unlike other infrastructure it is perceived to be ‘green’ and ‘environment friendly’. Humans, however, have definitely overlooked the other side of the problem: if the trees ever find
their life ‘urban-friendly’?
Benefits of urban forests have been catalogued in voluminous records, starting with school textbooks to the United Nations reports. These benefits are social, economic, psychological and environmental. They include energy benefits in the form of reduced air conditioning, reduced heating by shading buildings, homes and roads, absorbing sunlight, reducing ultraviolet light, cooling the air, and reducing wind speed and purifying the air. Economic benefits, which probably incentivize the public policy towards urban forestry, include enhanced land value where the urban area is green. Trees and associated greenery at and around work place enhance workers’ productivity. Urban forests also reduce air pollution, reduce land degradation, absorb rainwater and attract the birds.
Trees, it seems, also contribute to making corrections in misdeeds of humans in their urban planning. The storm-water management system, wrongly designed cannot hold the floods in case of excessive rainfalls. Street trees with iron-grates underneath them hold that excess water. The soil around the trees also filters the contaminated water by absorbing and processing it into less toxic substances.
A view of greenery from the window and walk through the row of trees is known to reduce the stress of hustle of urban life and revive the drained energy. The research has been carried out on psychological and health benefits of urban forests. Research has shown that children in kindergartens if taken regularly to the forest, develop better skills in reading, social activities and also in mathematics.
What is neglected and simply overlooked is that the urban environment is extremely stressful to the trees! Their roots have limited space to spread and deepen. Most of the soil is already degraded due to construction materials and chemicals used. Poor quality of soil, limited availability of water, polluted air due to automobile exhaust, heated surroundings due to heat expelled by the air conditioners –all contribute to the stressful surrounding for the healthy growth of trees.
Recently the researchers have started looking at the ‘health-stress’ for the trees. Various constraints on city-trees limit their average lifespan to only 32 years as compared to average of 150 years for trees in rural setting. The life span even reduces to 13 years if the trees are in the center of the large cities.
It is as clear as fresh leaves, that if we would like the urban forest to be useful to mankind, we need to nurture them as if they are in healthy rural surroundings.
Weak and unhealthy trees would not be effective in absorbing carbon dioxide and cannot be counted as effective carbon sink in our endeavor to mitigate climate change. The tree leaves and branches covered with dust and chemical smog cannot attract birds, but only stray dogs.
We are literally missing the forest for trees! END
Rajendra Shende , Chairman TERRE Policy Centre.