Trees on city streets cope with drought by drinking from leaky pipes

The trees that grow in the streets of the city are more resistant to drought than those of the parks because they drink in an unusual source of water: fleeing pipes.

After long periods with little rain, the water levels and the sap flow tend to decrease more in the trees that grow in the parks compared to those of the streets, but we did not know why.

To investigate, André Poirier at the University of Quebec in Montreal, in Canada, and his colleagues have taken samples from Trunk from Norway Maple and Silver Maple (Acer Platanoides And Acer Saccharinum) in parks and streets in two Montreal districts. They measured the levels of various lead isotopes – atomically distinct versions of metal which can indicate unique origins – then linked the levels of isotopes to the recent history of trees while counting the trunk rings.

While the trees of the park contained lead isotopes normally associated with air pollution, street trees had isotopes found in lead water pipes, which were made with metal geologically metal in neighboring mines.

Maps should consume about 50 liters of water per day. Given that street trees cannot get a lot of it from rainwater, which falls on concrete and drains in the sewers of the city, Poirier says that the most likely explanation is that it comes from the hoses of Montreal, which lose 500 million liters of water per day.

“The good news is that you can continue to plant trees in the street, because it makes people happy to have trees, and they will survive better than in the parks,” explains Poirier, who presented his work at the Goldschmidt conference in geochemistry in Prague, in the Czech Republic, July 8.

“The scale of water use by these street trees is phenomenal and it goes against the common paradigm, that is to say that you think that the trees of the park would be much healthier,” explains Gabriel Filippelli at the University of Indiana.