In 2001 there were 1.3bn trees in England. That’s 25 for every person in the country, the highest numbers since the first world war. One article predictedthat in 2020 there would be more trees in England than in 1086, when 15% of the country was cloaked in woodland. Part of the reason for this buoyant outlook was the country’s response to the great storm of 1987. We mourned for our ancient yews and the beeches of Chanctonbury Ring. Petitions were drafted, many thousands of saplings were planted. We rebuilt our woods with solemn and impassioned dedication.
The predictions will not fall short. Across the UK, the number of trees has sharply increased. In 2015 there were 3bn trees, the equivalent of 47, a sizeable copse, for every person, around twice as many as in 2001. These statistics might evoke a bosky eden where the wild wood is reclaiming the land, yet recent years have also seen a return of large-scale felling, with Network Rail’s plans to cut down millions more trees the latest example.
Network Rail’s view of trees is understandable. Leaves on the line can cause trains to overshoot stations, and branches and entire trees falling on to tracks cause delay or halt journeys. Between March 2016 and March 2017, 233 trains collided with fallen trees. The effect on customers cost the company hundreds of millions of pounds in compensation per year.
But it is unlikely that Network Rail or Sheffield council – which has felled around 6,000 trees as part of a project to “improve the condition of the streets” of the city – have considered the impact on humans caused by the removal of so much verdure. Research shows that time spent among trees causes levels of the stress hormone cortisol to decrease, lowers blood pressure, increases the number of active natural killer cells, so boosting immune function – and improves mood and concentration. In Japan, shinrin-yoku, or “forest bathing”, is a widespread approach to improving physical and mental health. Many of these beneficial effects are delivered by both phytoncides – volatile oils released by plants and trees to fend off infection – and by contact with beneficial soil bacteria.