Old age, choked roots and arid soil conditions are some of the reasons that trees in Delhi have been particularly prone to being uprooted in the storms during the last month-and-a-half.“We are losing 200 trees every year in our area itself; the most vulnerable period is between May and July,” said New Delhi Municipal Council (NDMC) horticulture director S Chellaiah.
In areas under the NDMC, what contributes to the weakness is the fact that most trees were planted between 1920 and 1935, during the construction of Lutyens’ Delhi, and are more than 80 years old. Chellaiah said trees like neem have been falling especially rapidly because dead cells are formed as they approach the end of their lives, rendering them weak and unable to uptake water and nutrients. However, according to an advocate with the National Green Tribunal (NGT), Aditya Prasad, the primary cause behind tree death is man-made.
“Roots are cut and damaged because of digging of trenches and the use of machines such as earthmovers by civic bodies. The civic departments should consult the horticultural department before authorising any digging because it causes the gradual decay of these trees, making them susceptible to collapse,” he said.
Both Chellaiah and South Delhi Municipal Corporation (SDMC) horticulture director Alok Kumar also flagged the lack of water percolation into the soil because of concretisation of the city, and the network of underground cables that choke the roots.
Kumar also pointed to the unconducive nature of the soil itself. “Delhi has a thin soil layer below which lies a stone crust, which doesn’t allow roots to grow deep and renders the trees weak.”
While Kumar said continuous replantation in some density is a solution, Chellaiah believes that a way to add 50 years to the lives of existing trees is by resorting to heavy pruning of branches to reduce pressure on weakened roots. Prasad said replantation will not solve the problem, and that the green tribunal orders — preventing excavation within one metre radius of trees and directing the removal, without heavy machinery, of concrete structures within a metre of a tree — have to be followed.