Ancient Beech Tree Diversion

Reasons for the path diversion and fencing around the Ancient Beech

The Ancient Beech pollard on the lower path in Foxley Wood ["Mother Beech", Tree ID No. 48125 in the Ancient Tree Inventory] has been a cause for concern to Croydon Council for some years, due to an area of basal decay not normally visible to passers-by as it is on the other side of the tree from the path. The condition of the tree has lead to a decision to divert the path out of the area into which it, or branches from it, could fall, and to fence the area in order to minimise any risk of harm which the tree may pose to users of Foxley Wood. As the tree is 23m tall, the exclusion circle must be 23m in radius. Exclusion will also enable compacted soils around the tree to recover their structure. This way of protecting ancient trees is increasingly used on conservation sites elsewhere, to maintain their habitat and visual value rather than fell them.

The decay may have been caused by the pruning of a large limb, the cavity shows fruiting bodies [brackets] of Ganoderma australe [Southern Bracket] and has in the past also had both forms of Kretzschmaria deusta [Brittle Cinder Fungus]. That the latter has not been seen fruiting for several years may be a hopeful sign that resources available to the fungus may have been used up and the decay compartmentalised [reference: CODIT]. Both of these fungi degrade the lignin in wood which provides structural rigidity. The tree can sense the increase in flexing and can respond by growing compensatory wood, of greater strength and density than normal wood. This can be seen in the arch of new wood around the cavity, which may actually be stronger than the original wood structure of the trunk. However, it is not known how far any decay may have extended up into the main branches, which could break out from the pollard union.

The tree was reduced in height by pruning several years ago to bring the crown below those of surrounding trees and reduce the potentially destructive effect of wind loading. Beech, especially over-mature specimens, are conventionally thought to respond poorly to pruning, but the regrowth of epicormic shoots along the pruned branches has been surprisingly good, creating a new lower, inner crown of new foliage which is a most hopeful sign of the continuing vigour of the tree and bodes well for an extended old age. Beech do not normally live more than 200-250 years, though pollarding can extend life by up to double the normal. The age of the tree was estimated 15 years ago [using the method in the Forestry Commission Technical Information Note:- "Estimating the Age of Large and Veteran Trees in Britain"] at 260 years, so now is estimated as 275 years.

Rather than remove the risk of harm to users of the wood by felling the tree, it’s extraordinary value as an ancient tree; the biodiversity of the community of organisms to which it is a host, and an ecology in itself; its status as a local icon of the wood, and as a veteran tree registered on the national database; grant funding from the Mayor of London’s Greener City Fund was applied for and won to create the path diversion and install fencing. The existing rolled stone path will also be removed and the soil around the tree will be improved and decompacted by adding a mixture of composted leaf mould and charcoal fines [biochar]. This is intended to improve the condition of the rooting zone of the tree with natural materials to assist its defence against the decay fungi. The work will be carried out by a contractor, assisted by the Friends and by Croydon TCV between the 5th and 16th of October. This will entail closure of the path.

The decay may have been caused by the pruning of a large limb, the cavity shows fruiting bodies [brackets] of Ganoderma australe [Southern Bracket] and has in the past also had both forms of Kretzschmaria deusta [Brittle Cinder Fungus] That the latter has not been seen fruiting for several years may be a hopeful sign that resources available to the fungus may have been used up and the decay compartmentalised [reference: CODIT]. Both of these fungi degrade the lignin in wood which provides structural rigidity. The tree can sense the increase in flexing and can respond by growing compensatory wood, of greater strength and density than normal wood. This can be seen in the arch of new wood around the cavity, which may actually be stronger than the original wood structure of the trunk. However, it is not known how far any decay may have extended up into the main branches, which could break out from the pollard union.In clearing the proposed route for the diversion, three badger holes were found adjacent to, and one directly in the route. Monitoring of these holes over several months, including with trail cameras, showed that only one is active and this is concealed behind a fallen tree. Advice was obtained from the East Surrey Badger Protection Society which has inspected the site and assisted in obtaining the necessary authorisation and licence from Natural England for work to take place adjacent to a sett.

It is understood and expected that restricting access to such a well-loved tree will be distressing to many users, some of whom have described it to the Friends as ‘’their’’ tree. So many people have engaged closely with the bark, the trunk, climbed it and swung from the branch swings, admired and revelled in it’s glory, brought children to experience its extraordinary character. But we need to protect the tree, and the users, who will at least still be able to see it, even if at something of a distance, via vistas we will create through the surrounding trees, and from re-sited benches, hopefully for many more years to come. The only alternative at present is to fell it, and no-one wants that….

If you have any concerns or questions, please contact the Friends of Foxley via this site or our Facebook page [Friends of Foxley Wood].

Written by Anthony Mills, Dip.Hort[RHS]; Tech Arbor.A.. Arboricultural Advisor for Friends of Foxley 19th Oct 2020