Trees play an important part in regulating pollution and climate in towns and cities, but are falling foul of insurance companies and councils who are felling healthy, mature trees in their thousands.

Report Thursday 3 April 2008: guardian.co.uk  video

An unusual contest is taking shape during the London mayoral campaign: candidates are fighting to see who can promise to plant the most trees. Boris Johnson has pledged to put up 10,000 street trees in London while Ken Livingstone has described the Conservative candidate's target as "incredibly unambitious" and claimed he will plant 600,000 trees by 2012.

All the time, however, trees are being removed from the capital, and in other cities across the country, because of health and safety issues, security fears and, most commonly, insurance claims and threats from loss adjusters.

For the Gildea family, the mayoral promises are too little, too late. This spring, just as their magnificent plane tree should be coming into leaf in their garden in south London, they have instead had to watch it get chopped down after they were threatened with legal action by an insurance company.

Tiny roots from the tree had been found in a neighbouring garden, raising the possibility that an insurance claim could be made against the tree if subsidence—sometimes caused by tree roots causing clay soils to dry out and contract—was found in nearby houses. Such claims—even if spurious—routinely lead to the removal of street and garden trees in cities.

Denis and Hazel Gildea, aged 84 and 83, could not watch the destruction of the 150-year-old tree, under which their 5 children and 18 grandchildren had played safely for the last 54 years.

"My parents went away for three days. They couldn't bear to see it come down," said Edward Gildea. "It has left the most huge void."

One tree surgeon enlisted to fell the tree refused because it was such a fine tree and he judged it no danger to anyone. John Welton said: "I can't believe that such a beautiful tree, a particularly well-balanced and well-structured specimen, has to be felled. It is crazy that an insurance company is insisting on its removal for reasons that cannot be proved and haven't been substantiated."

Trees in towns and cities have many benefits for health and the environment. Shelter and shade from trees can reduce energy costs, cut pollution and enhance outdoor spaces.

Trees also slow the rate at which rainwater hits the ground, helping to reduce the risk of flooding, and bind the soil to prevent erosion.

"Trees help to provide better air quality in towns and cities by trapping pollution on their leaves," said Graham Simmonds, the chief executive of trees for cities, a charity working with communities to plant more trees in urban areas.

"In the fight against global warming, trees play their part in two ways—they absorb CO2 as they grow and there is also what we call the 'heat island effect'—which means where you've got buildings with trees around them they'll help to moderate the climate by keeping warmer in winters and cooler in summer, cooling the city and reducing energy use."

A spokesperson for the insurance company said it would never remove a customer's tree from their property against their wishes.

"In this case it is clear from the technical evidence we have received that the tree is causing damage to a neighbouring property. After full investigation of various options, we've come to the unfortunate conclusion that the only way to prevent further damage is to remove the tree.

"We have given this recommendation to Mr Gildea and have advised him that if he refuses to remove the tree then we will no longer be able to provide cover for any claims resulting from the damage the tree causes.

"Whilst of course the decision to remove such an old and well established tree is not one we would take lightly, we have a duty to prevent damage to property."

Mr Gildea welcomed the mayoral candidates' promises to plant more trees but pointed out it would only benefit the urban environment if they were large, broadleaved trees. Another trend has been to plant small flowering or fruit trees which, the authorities argue, pose less risk than bigger trees.

Trees are being removed across the greater London area. Figures submitted to the London assembly last year found Harrow lost 5,000 street trees over the previous five years and was only able to replant 1,750, leaving a total of 16,000. That figure was typical of trends in many boroughs and does not include trees removed from private gardens like the Gildeas'.

There is now a gaping hole on the Gildeas' horizon but the family are determined not to let the insurance industry change the skyline forever: they have vowed to plant another plane tree next to the stump of the felled tree to celebrate Hazel Gildea's 84th birthday.

"When that is mature in 100 years time I'm confident the insurance company won't exist to be worried about it," said Mr Gildea. "It will be a symbolic two fingers for the insurance industry."

http://www.guardian.co.uk/environment/2008/apr/03/conservation.wildlife