Looking after our veteran trees at Ashridge Estate

Fall of a giant

In 2015, Ashridge Estate’s most famous tree, the Frithsden Beech, cleaved in two. There was nothing that could have been done for this star of many films, including Harry Potter and the Goblet of Fire, Les Miserables and Sleepy Hollow. But it was a wake-up call that the work already started to look after the estate’s veteran trees should be prioritised.

Size of the task in-hand

The Ashridge ranger team have identified over 1000 ancient and veteran trees that would benefit from help. A veteran tree is not quite the same as an ancient one. It can be hard to tell the age of an ancient tree but an oak would not be considered to be ancient until it was at least 400 years old. 

Veteran trees are old trees which are notable for their features. ‘These could be dead branches, holes, hollows, areas of rot or a fork with a watery pool,’ explains Ashridge’s ranger Ben Byfield. 

Playing their part

Veterans are vital because ‘they play such an important role in the ecosystem and support so many rare species,’ says Ben. ‘Invertebrates associated with old trees are incredibly fussy as to where they like to live. It could be in a rot pocket, in deeply fissured bark or in the hollow trunk. Young trees just don’t have that same diversity of habitats.’ 

Throughout Europe ancient and veteran trees are now rare. Ashridge is a nationally important site for these trees and their associated rare species.

Halo-releasing

Research into ‘halo-releasing’ to prolong the life of veterans has been going on for the last 30 years. Haloing is based on the theory that as trees age, they become less tolerant of shade. When trees that began life in an open area become surrounded by younger trees, they suffer due to a lack of light. If the lower branches are shaded out by saplings, their lives can be shortened by 100 years. 

How it's done

Area ranger, Chrissy and her team clear the encroaching trees that have grown up around the veterans in a 5m halo around the tree. Five years later, a further 5m band is cleared. ‘We do it gradually so as not to “shock” the tree,’ she says, ‘They’re very sensitive to changes in wind dynamics and humidity, so we have to be gentle or we could end up hastening their demise.’

‘Haloing is the exact opposite of automated commercial felling. You need to be careful not to clatter the veteran with the tree you’re removing,’ explains Chrissy. ‘We use hand chain saws and keep the heavy machinery as far away as possible to avoid ground compaction so that we don’t damage the roots or reduce the air pockets in the soil.’

‘It feels important,’ says Chrissy, ‘Ashridge is such a special place and these trees should long outlive us. On a personal level, I feel it’s a huge privilege to spend my working life making a difference and maintaining it for the future.’