Stressed street trees: mapping the urban forests to save them – and us

City trees are under increased threat but research tools show that looking after them will lower temperatures, prevent flooding and reduce pollution

Standing proud at the intersection of Queen and Little Bourke streets in Melbourne's central business district is one of the city's beloved London plane trees. It's in declining health and will probably need to be replaced in a decade or so. I know this not as an arborist, or even as a keen observer, but because the City of Melbourne has assiduously assessed, mapped and put online all of its more than 70,000 street and parkland trees.

"It's quite extraordinary the amount of data that we have on our trees," says a councillor, Cathy Oke, who chairs the city's environment portfolio.