London’s trees are suffering from droughts and diseases as the impacts of climate change are worsening, experts have warned at a City Hall meeting.
Extended periods without rainfall have tested the resilience of several of the capital’s tree species, raising the urgency of learning lessons from other cities, the London Assembly’s environment committee heard on Wednesday.
“We’re seeing [the] decline of birch, decline of rowan, and we’re seeing [a] prevalence of sooty bark disease affecting sycamore, which is of concern, because that follows a period of dry weather,” said Craig Ruddick of the London Tree Officers Association.
“If we have consecutive dry summers, I’m concerned about what the overall impact is going to be on sycamore, which is a significant contributor to London’s canopy.”
Kevin Martin, head of tree collections and arboriculture at Kew Gardens, said fresh approaches to urban planting may be needed to help maintain that canopy.
“From a lot of the research we’ve done, a lot of the species that we’re currently planting in our urban environments are just not suited to be planted in urban environments,” he said.
“We have to think really carefully now about getting the species selection right, trees that we know have the plasticity to deal with drought stress like we’re seeing now.
“Also, combined with that, is how we plant trees. I’ve just come back from Malmö in Sweden and they are very far advanced of what we’re doing now in London. They’re even going to the stage where they’re creating their own soils, so when they do get rain, they can hold the moisture for a lot longer.
“They’re using a mix of perlite and biochar and also soft, organic mulch, and they’re really buying into it and increasing their planting pits. So there’s lots of things we have to look at to get the establishment of trees in London.”
He added that there was no getting away from the fact that London is “a big urban heat island” which typically records temperatures higher than in rural areas across the south of England.
The British public’s concern for trees and their welfare appears to have grown, Mr Martin pointed out. The felling of an ancient oak in Enfield, and the destruction of the Sycamore Gap tree in Northumberland, have both been given significant coverage in national news outlets over recent weeks.
“We're going through a really big shift, culturally, in the UK,” said Mr Martin. “I was a commercial tree surgeon for many years and trees were always seen as a nuisance. It’s only in the last decade that we’re starting to see this really big cultural shift, where there is a want, via the general public, to start protecting some of these trees.
“It’s an amazing thing for me as a ‘tree person’ to start seeing that shift, and things like the Sycamore Gap have definitely brought that to the forefront, but I do think we need to keep pushing on with that and don’t let it go out of the public eye, because as soon as that news story stops, it will all be forgotten about again.”
Abby Crisostomo, City Hall’s head of green infrastructure, said mayor Sir Sadiq Khan remained committed to his goal of increasing London’s tree canopy by 10 per cent, having already funded the planting of more than 600,000 new trees since his election in 2016.
Conservative assembly member Keith Prince pointed out that prior to his election, Sir Sadiq had promised Londoners he would plant two million trees in his first term alone, though this pledge did not end up appearing in his formal manifesto.
