Pollarded

[Arleen Smelko]

Pollardingis a pruning system involving the removal of the upper branches of a tree, which promotes the growth of a dense head of foliage and branches. In ancient Rome, Propertius mentioned pollarding during the 1st century BCE.[1] The practice has occurred commonly in Europe since medieval times, and takes place today in urban areas worldwide, primarily to maintain trees at a determined height or to place new shoots out of the reach of grazing animals.[2][3]

Traditionally, people pollarded trees for one of two reasons: for fodder to feed livestock or for wood. Fodder pollards produced "pollard hay" for livestock feed; they were pruned at intervals of two to six years so their leafy material would be most abundant. Wood pollards were pruned at longer intervals of eight to fifteen years, a pruning cycle tending to produce upright poles favored for fencing and boat construction. Supple young willow or hazel branches may be harvested as material for weaving baskets, fences, and garden constructions such as bowers. Nowadays, the practice is sometimes used for ornamental trees, such as crape myrtles in southern states of the US.[4][5]

Pollarding tends to make trees live longer by maintaining them in a partially juvenile state and by reducing the weight and windage of the top part of the tree.[6] Older pollards often become hollow, so it can be difficult to determine age accurately. Pollards tend to grow slowly, with denser growth-rings in the years immediately after cutting.

Pollarding was preferred over coppicing in wood-pastures and other grazed areas, because animals would browse the regrowth from coppice stools. Historically in England, the right to pollard or "lop" was often granted to local people for fuel on common land or in royal forests; this was part of the right of estover.[7]

An incidental effect of pollarding in woodland is the encouragement of underbrush growth due to increased light reaching the woodland floor. This can increase species diversity. However, in woodland where pollarding was once common but has now ceased, the opposite effect occurs, as the side and top shoots develop into trunk-sized branches. An example of this can be seen in Epping Forest, which is within both London and Essex, UK, the majority of which was pollarded until the late 19th century. Here, the light that reaches the woodland floor is limited owing to the thick growth of the pollarded trees.

Pollards cut at about a metre above the ground are called stubs (or stubbs). These were often used as markers in coppice or other woodland. Stubs cannot be used where the trees are browsed by animals, as the regrowing shoots are below the browse line.

"Poll" was originally a name for the top of the head, and "to poll" was a verb meaning 'to crop the hair'. This use was extended to similar treatment of the branches of trees and the horns of animals. A pollard simply meant someone or something that had been polled (similar to the formation of "drunkard" and "sluggard"); for example, a hornless ox or polled livestock. Later, the noun "pollard" came to be used as a verb: "pollarding". Pollarding has now largely replaced polling as the verb in the forestry sense. Pollard can also be used as an adjective: "pollard tree".[10]

Pollarding a tree is usually done annually, and would need to be carried out every few years to avoid potential problems. This usually involves hiring an arborist, so can be expensive. Why not consider the following before pollarding:

Initially, the new branches are held weakly in place as they grow rapidly from underneath the bark, rather than from within the tree. As the wood lays down annual growth rings, the union strengthens, often forming a thickened base where the shoot meets the trunk. Over a number of years, a swollen 'pollard head' forms where new shoots grow each year.

Seek advice from an arborist before doing any work. Although having a tree pollarded regularly is expensive, an overgrown pollard may require more surgery to remove larger parts of the tree at a greater height.

Trees with weaker wood prone to producing multiple shoots, such as poplar (Populus) and willow (Salix) can become hazardous. Some of the weakly-attached branches can break off and fall to the ground. Ideally, try to return to a frequent cutting cycle and have an arborist carry out a safety check regularly.

A similar problem can occur with trees such as beech (Fagus sylvatica), oak (Quercus robur) and sweet chestnut (Castanea sativa). The branches become heavy when pollarding lapses for several decades, and these may break away in windy weather. Consult an arborist, if you are in any doubt.

Pollarding is the technique of regularly pruning trees or shrubs back to a trunk to form a head of branches. The trunk height can vary, with around 1.5 to 3m usual in a garden situation. Pollarding is done for several reasons: to restrict growth of a tree in a confined space, to create a formal shape, to encourage the production of stems with more colourful leaves and decorative bark, both of which are brighter on the young, vigorous growth that hard pruning stimulates, and lastly to produce larger than usual leaves. Pollarded trees are a common sight in cities and particularly in many European countries. The practice of pollarding should be done as a form of training from when the tree is young and should not be used as a means of reducing growth on an older tree.

Pollarding is similar to coppicing. The difference between the two is that coppicing involves cutting a tree or shrub back to a stump at ground level, whereas a pollarded tree has a trunk that broadens with age and a head with stubs of branches from which new shoots grow each year. In traditional woodland management, both techniques were used for practical reasons, such as firewood production and to harvest straight stems for fencing.

Start by planting a young tree with a single stem. Once the trunk or stem has reached the height you want, cut back the branches in late winter or early spring. Select three to five branches to keep as the basic framework and cut these back almost to the trunk. This hard pruning stimulates the growth of many slender shoots from each stump.

Any shoots that grow from the trunk below the pollarded head should be taken off as soon as they appear, which can be any time during the growing season. Ideally remove by snapping off, rather than cutting which can encourage even more shoots to develop.

The practice of pollarding is quite likely one of the oldest forms of pruning, outside of fruit tree pruning, that is still widely used today. Pollarding was developed in medieval Europe with purely utilitarian purposes, which likely looked very much like topping. Upper tree limbs were removed and cut back to lower portions of the main stem or large scaffold branches. During those times, wood was essential for heating homes and cooking, so wood could become a scarce commodity. Cutting down a tree would not be of long-term benefit, as the tree would be gone.

This constant need for wood was solved by allowing the cut back limbs/stems to grow back small shoots. These shoots would be allowed to grow for one to two years before being cut back and harvested. Each time the shoots are cut back, they are cut in a manner that leaves a small amount of wound wood and shoot material which slowly turns into a large knuckle at the end of each branch. The development of these knuckles prevents decay from spreading down into the remainder of the tree, and does not damage the tree. While there is little need to pollard trees for utilitarian means today, it is still a very practical pruning method that could be of great benefit in many urban settings, even now.

By pollarding trees, it is possible to maintain trees in harsh urban settings. For example, in sidewalk planters, the trees are kept small by limiting their growth up to the height where the knuckles are maintained. Even large species trees can be kept small as seen in the photos of London Plane trees (Platanus x hispanica), maintained as small street trees along Ghirardelli Square in San Francisco. Left to their own devices, these trees could easily grow 50 to 70 feet tall, even in the limited soil volume. Sidewalks would be destroyed, maintaining building clearance would be nearly impossible, leaf debris would be drastically greater, and all work would have to be done by skilled arborists (whose work would be done aloft).

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