Over the years, we’ve had many inquiries from members regarding continuing the practice of pollarding the London Plane (Sycamore) trees lining the main streets of LHA. Pollarding is a pruning system in which the upper branches of a tree are removed, promoting a dense head of foliage while keeping the tree smaller than it would naturally grow. With the City no longer covering the cost of pollarding our street trees, LHA has inherited the tree maintenance and associated costs.

We have researched ending the practice of pollarding our street trees, including opinions from several East Bay arborists, Oakland’s Tree Services division, on-line research, and conversing with the mayor and arborist of two small towns in France, whose town squares are filled with both pollarded and never-pollarded Sycamores.

To reach a definitive answer for LHA’s street trees, this winter I researched the 3,000 year old Epping Forest on the edge of London, England. Why choose this place? Epping Forest is internationally renowned for its ancient (5 centuries old) pollarded trees – primarily Oak, Beech and Hornbeam. Epping Forest has a diverse landscape rich in flora (650+ plant species), wood-pasture, grassy plains and ancient trees: of the over 90,000 trees in Epping Forest, 50,000 are lapsed pollarded trees.

In medieval times, Saxon and Norman kings protected Epping Forest under Forest Law. It’s now entrusted to the City of London as Conservators by the Epping Forest Act of 1878. The City is responsible for the Forest (flora, fauna, grazing, future, people, uses, etc.) and provides park rangers, arborists, and specialists to execute the Forest’s management plan. Their conservation breadth ranges from clearing ponds to rediscovering the lost art of pollarding trees.

In my correspondence with Epping Forest Biodiversity Officer Andrew Froud, I provided the details of the London Plane trees within LHA – 434 trees planted in the sidewalk strips that average 80 years old and have been pollarded every 5-7 years for decades. I let him know that we are interested in the possibility of ending the practice and I asked about his experience in rehabilitating formerly pollarded London Planes. Below is his very informative response:

Dear Patty,

Here at Epping Forest (Essex) we have over 50,000 veteran lapsed pollards. All of these trees are over 4-500 years old but largely cutting (pollarding) ceased (lapsed) about 150-200 years ago. We have 3 main pollarded tree species Common Beech, English Oak and Hornbeam. In the last 30-40 years we have begun the process of re-pollarded these lapsed pollards but with the trees being 150 years+ between cutting rotations this work is extremely difficult and difficult to predict the trees’ response to this management. We do have Hornbeam trees now in a cutting rotation of between 10-15 years.

In regards to not pollarding a tree anymore as a management option. Once a tree (whichever species) is pollarded, especially if it has been pollarded, as you mention “for decades” there are a number of risks associated with then leaving it to grow. When a tree is pollarded the new growth that is produced is not as strong as a branch of a naturally grown tree, the new growth is weakly attached to the tree and begins to break/fail and fall out of the tree from an early age. Pollarding for decades also creates areas of decay/hollowing inside the tree which is not always visible externally. Decay/hollowing is not a problem for the tree it is part of the natural process and does have some advantages for the tree except if the tree is then allowed to grow naturally where the trunk of the tree (due to decay/hollowing) cannot support the weight of the branches/stems that have been allowed to grow. We have this problem here at Epping, trees are tearing themselves apart under the weight of the crown. Allowing the trees to grow will also increase root production as the tree would require more water and stability as the new crown develops.

I understand the problems with the expense of pollarding trees every 5-7 years but unfortunately, once you begin to pollard trees it is not then advisable to allow these to grow naturally especially if they are growing in a sidewalk strip. I imagine if you spoke to professional arborists (tree people) in your area or professionals from the City of Oakland they would advise the same thing. You may be able to increase the length of time between cutting but you would need to seek advice and a site survey from a local professional before you do this.

Kind Regards,
Andy

Andrew Froud,
Biodiversity Officer, Open Spaces – Epping Forest, City of London