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Traditionally, pollarding is the process of managing trees to obtain repeated crops of various sized wood. Here on the Common it is used to extend the life, biodiversity and contribution of 'veteran' trees.

What is a veteran tree?

Unlike an ancient tree, a veteran tree can be any age, but it is a tree which shows ancient characteristics and good biodiversity value such as a hollowing trunk, cavities, flaking bark, sap runs, good deadwood habitat, to name a few. These features may not just be due to age, but could result from natural damage, management, or the tree’s environment. Ancient trees are all veterans, but not all veterans are ancient!

What is pollarding?

Pollarding is the historic process of managing trees to obtain repeated crops of various sized wood, which were used for fencing, firewood, charcoal, fodder and faggots. It is similar to coppicing (where the trees are cut to near ground level) but instead the trees are cut so that the regrowth is out of reach of browsing animals.

The length of the cycle, i.e. the time between cutting would depend on the species and the subsequent use of the wood. Ash and elm were the most palatable to animals and so were cropped in the summer on 5-10 year cycles, with the woody branches of ash being used as handles for tools. Whilst oak was left for longer to provide larger diameter firewood whilst the hornbeam pollards that surround London were on a short rotation to supply the bread ovens of the city.

The value of pollards to wildlife

Pollarded trees, in particular oaks (as they support a very high number of species) are incredibly valuable to nature conservation. The cyclical cutting at the top of the bolling (main stem) causes irregularities as numerous different cut surfaces are exposed. Small ‘pockets’ form that may often hold water and combined with the exposure of cut surfaces allows for the development of decaying wood and hollowing, brought on by certain wood decay fungi.

These wood decay fungi are not to the detriment of the tree but instead are a natural part of the ageing process of a tree. These keystone fungi provide the crucial habitat for over 2000 different species of invertebrates that depend on decaying wood. Furthermore, this decay provides the cavities used by nesting birds and roosting bats. Pollarding speeds up the process by which these important habitat niches are created, thus making the tree more valuable to wildlife in a shorter length of time.  In comparison, if left to develop naturally (unmanaged), research has found that only 1% of oak trees younger than 100 year olds have hollows, and 50% of those aged 200-300 year old have hollows.

The regular cutting of a pollard keeps the trees in a juvenile state as the removal of the canopy encourages and stimulates the rapid development of fast growing shoots. Furthermore, these short and squat trees, with hollowed out stems are much more resilient to storm damage in comparison to maiden trees (a tree with a natural, unmanaged crown i.e. a coppice or a pollard) hence why most of our oldest trees in the UK are lapsed pollards!

Where have all the pollards gone?

Working pollarded trees were a familiar landscape feature across the UK often associated with wood pasture (dating back to the 12th century) but also in royal forests, commons, riverbank trees and along boundaries.  Over time, the loss of commoner rights, the decline in interest of locally sourced small diameter wood and the industrial revolution all played a part in this management process dying out.

This has resulted in neglected pollards carrying larger branches that are weakly attached to a decaying bolling. These large limbs become susceptible to storms, and if sufficient damage is done it will cause the long term demise of the tree and subsequent loss of a unique habitat, and a complete ecosystem that was dependent upon that tree.

Neglected (lapsed) pollards cannot easily be re-pollarded as the long gap between cutting cycles may mean that they do not have the vigour to respond or that these large limbs may possess habitat features of their own and so need to be retained. Instead management aims to gradually encourage the tree crown to retrench and lessen the ‘sail’ of the tree so the potential impact for wind damage is reduced. However, on certain sites they have been able to restore old pollards and bring the trees back into a management cycle.

Pollard creation: Barnes Common

Barnes Common currently has nearly 2000 oaks under 100 years old with very few, if any, over 200 years. This current generation gap poses a risk to habitat continuation. Therefore, we have initiated a range of new pollards across the common. As well as providing future wildlife habitat the pollards also combine cultural and historical value, restoring a lost management practice to a Common.

Pollarding has been carried out by Jamie Simpson, a specialist in ancient and veteran tree management, and assisted by FoBC conservation staff. Jamie has been creating new pollards in some of the most important wood pasture sites across the UK; Moccas Park NNR, Croft Castle and Richmond Park NNR (where he has created over 200 new pollards) and has published guidance on pollard creation.

Pollards have predominantly been created on young oaks, with the exception of a single sweet chestnut. Many of the young oaks that have been pollarded are growing on areas of Lowland Acid Grassland (LAG) a habitat of national and borough importance. Therefore, by keeping the oaks in a smaller form and restricting limb spread you reduce nutrification of the ground by limiting leaf litter. This also ensures sunlight reaches the grassland beneath thus preventing excessive shading and the colonisation of a bramble understory, which is common across the common. Therefore, pollards created across areas of LAG will have a twofold benefit; restoration and improvement of the acid grassland as well as habitat creation associated with oak pollards.  

All new pollards have been recorded, photographed and will be monitored to add to the research base on creating new pollards. There is a recognised lack of photographic or other documentation on the practical establishment of young pollards.  This presents a unique opportunity for FoBC to contribute to scientific research, whilst improving wildlife habitat.

If you would like to know more, please contact Will

Will Dartnell. January 2021

Further Reading

Development of Tree Hollows in Pendunculate Oak (Quercus robur)  Forestry Ecology & Management

Ensuring Ancient Trees for the Future: Guidelines for Oak Pollard Creation   Ancient Tree Forum

Fungi and Ancient Trees   Ancient Tree Forum

Invertebrates and Ancient Trees  Ancient Tree Forum

Is Active Management the Key to the Conservation of Saproxylic Biodiversity? Pollarding promotes the Formation of Tree Hollows  NCBI

Oak-associated biodiversity in the UK (OakEcol)  UK Centre for Ecology & Hydrology

 

 

 

 

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