Why trees count in economics
It is commendable that the number of states which have taken the initiative to invest in the environment, especially in tree planting campaigns, is increasing. Lagos is particularly commendable because it has achieved a feat of planting some 4.6 million trees in the last five or six years. Indeed, in the past, investing in the environment was seen as the exclusive preserve of environmentalists obsessed with green environments.
Today, this is hardly the case as economists have evidence that urban vegetation has benefits which are enormous. And as our science evolves ways to effectively capture the benefits of greenery in cities, the case for them continues to be more forceful. Now, there are more works measuring the benefits of trees and green fields in the environment.
According to T. M. Das, a professor at the University of Calcutta, a tree living for 50 years will generate $31,250 worth of oxygen, provide $62,000 worth of air pollution control, control soil erosion, increase soil fertility to the tune of $31,250, and recycle $37,500 worth of water. These estimates, generated from a labyrinthine of calculations, give an inkling into the value of trees, even though the figures do not include the value of fruits, lumber or aesthetics they add to the environment.
Some years ago, a research paper published in the United States indicated that in Washington, per tree average annual net benefits was $1 to $8 for a small tree, $19 to $25 for a medium tree, and $48 to $53 per year for a large tree. These benefits were quantified on the basis that if trees are not present, homeowners or municipal governments would have to invest in additional infrastructure or equipment to remedy environmental problems resulting from their absence.
Globally, tree canopies intercept rainwater, thereby reducing the amount of water falling to the ground and running off into storm-water collection systems – thus potentially saving a community the materials and construction costs of a storm-water system built to conduct storm-water.
There is little doubt that ecological systems which include trees provide a myriad of benefits to society. They clean air and surface water, renew potable water, offset greenhouse gas emissions caused by fossil fuel, reduce energy consumption and even provide jobs for those who are employed to tend them.
At the micro level, there is also research which point to the effect of vegetation to work performance. In a survey carried out in the United States by Rachel Kaplan on dockworkers about their rate of illness and level of job satisfaction, it was discovered that those without environments enriched with vegetation claimed 23 percent more times of illness in the prior six months. Those with a view and adequate greenery claimed were less frustrated about tasks and generally more patient, felt greater enthusiasm for the job, reported feelings of higher life satisfaction, and had better overall health.
It is in recognition of these benefits that tree-loving celebrities like Leonardo DiCaprio and Coldplay have invested immensely in planting trees. The band Coldplay famously funded 10,000 mango trees in India to soak up emissions related to the production of their CD.
In dusty and densely-populated cities like Lagos, trees are inevitable and any government which has made it a point of duty to make the environment greener should be commended. This is true in other states like Delta, Akwa-Ibom, Anambra and other states where the government has deemed it fit to replenish the environment.
The initiative to increase the number of trees in our environment is laudable, but there are certain elements which should be put into consideration. Firstly, there should be focus on trees that have greater economic value. There is nothing wrong with planting trees that have nutritional and medicinal value.
Apart from this, there should be spirited effort at sustaining both the tree-planting process and the maintenance of the trees in the future. If this is not done, most of the trees will end up constituting a nuisance as they grow older.
While most of our people do not yet see the rationale behind these tree planting campaigns, our achievement in this area will be highly appreciated by the next generation, as they would inherit a more habitable, greener planet.
Obodo is a research analyst with BusinessDay.
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