‘Mumbai has very high tree-fall death ratio’

iNTERVIEW
Jeremy Barrell, Arborist

Veteran British arborist Jeremy Barrell says that expert intervention in tree-pruning and cutting is the only way to reduce incidents of tree falls.

Mumbai has witnessed six deaths due to tree falls this year (see below). The box also reveals that two such deaths occurred in May, which proves that citizens are not vulnerable only during monsoon. As we dig out the numbers, it comes to light that the six casualties were despite the BMC pruning a staggering 90,000 trees ahead of monsoon this year. Since 2012, 37 people lost their lives and 292 suffered injuries in tree/branch falls. Statistics obtained from the BMC’s disaster management unit reveal more than 24,000 tree-fall incidents since 2012.

The UK-based arborist (tree surgeon), Jeremy Barrell, who was in the city recently, said that the numbers were three times higher compared to any major city across the world. Barrell, who has spent nearly 40 years in the business of tree care, pointed out that unlike cities such as New York, London, Mumbai doesn’t have a system of calculating the value of trees. “Tree falls cannot be completely prevented, but their frequency can be reduced,” Barrell said.

♦ What are your views on Mumbai’s green cover?
Very impressive. Both the extent and the quality of tree cover in the city. Most of the trees I saw are in good health, but that’s not the primary issue regarding tree-safety; it is structural stability. I saw some trees that were obviously deteriorating structurally, due to poor pruning and lack of proactive management. Left on their own, the risk from these trees will increase. The biggest challenge come from large, mature trees, which provide the most benefits, but can also present the greatest risks.

♦ Mumbai witnesses deaths due to tree falls every year. Can such tragedies be averted?
Tree falls can’t be stopped completely, but their frequency can be reduced through proactive management. I have read the numbers in Mumbai Mirror. There are a few interesting, although crude, comparisons that can be made to the injury rates in countries such the UK, US, Australia, and Canada. In the UK, research suggests that there are about six deaths and more than 50 injuries in tree-related incidents in a year for a population of about 60 million. That equates to about one death per 10 million people, which is also reflected in the statistics from other countries mentioned. In Mumbai, you seem to have about the same death rate annually, but for a population of just less than 20 million, so the death rate seems to be about three times higher than the UK. These are just crude estimates, but they do indicate that the death rate is much higher than the UK. So why could that be? In the UK and the other countries, most trees that could cause harm are checked by trained professionals on a regular basis, and I suspect that this could be the way to reduce the incident rate.

♦ Most of tree-trimming here is done manually and by contractors who don’t have enough expertise in trees…
Again, I read about this in an article in Mumbai Mirror and I was quite surprised by it. This wouldn’t happen in the UK because it is widely understood that contractors without the necessary skills can cause more harm than good and increase the risk to people through poor work.


♦ Do you think tree-trimming is the only solution?
Tree management is a complex subject, which is why it has developed as a separate profession in many countries. It is called arboriculture, which is the management of individual trees in the built environment as opposed to forestry, which is management of timber production in the rural environment, or horticulture, which focuses on flowers and shrubs. Our experience in the UK is that professional tree management requires years of training, experience, and support from professional institutions. It cannot be done by other professionals such as landscape architects, foresters, architects, horticulturists, or road engineers, because they simply do not have the knowledge and experience to understand and identify tree defects early enough. My experience is that an effective way to reduce the number of trees falling is to manage them with proactive checks and pruning by trained professionals.

♦ How often must trees be trimmed?
Again, depends on local conditions and species. In the UK, if pruning is necessary at all, we aim to prune to avoid returning for five years, but that could easily be different in a climate where trees grow more rapidly compared to the UK.

♦ Putting a value on a tree is still not very prevalent in India…
There are now thousands of villages, towns, and cities around the world that have had their trees valued. All leading cities in the world either have a value of their tree asset or have an aspiration to do so because it establishes their sustainability credentials and allows them to be judged against an international standard. If Mumbai has an aspiration to be ranked as a top international city in terms of sustainability, then valuing the tree asset would be an essential step in achieving that objective.

♦ How is valuation of trees done?
In very general terms, there are two aspects of tree value that can be assessed and used independently, or together. Asset value is an estimate of what a tree is worth as it stands, based on a theoretical estimate of what it would cost to replace it like-for-like. For larger trees, replacement is often not feasible, hence the approach is an informed extrapolation based on measurable parameters. There is no one correct or universally accepted method of calculating tree value or the benefits that they deliver, nor does any one approach sit above others in the list of options. There are several mainstream approaches.

♦ Is planting two new trees for every tree cut enough?
A two-for-one replacement approach is very simplistic and would not normally be an adequate mitigation. It is widely accepted that it takes many small trees to replace a large tree and a more balanced approach is often to seek to replace the value rather than a numerical equivalent. In the UK, as a rule, at least 40 small trees are needed to reliably compensate for the loss of one large tree.