'Trogne' is the term used in the Loire for a pollarded tree ie a tree that has had its branches regularly pruned hard to a certain height, creating a very distinctive look. The practice is extremely common in the Loire, particularly for garden or street trees, but is often looked at rather askance by visitors from the United States, Britain and Australia, who are uncomfortable with the idea of, as they see it, interfering and controlling nature in this blatantly interventionist manner.
Pollarded Lime trees in the old camping grounds in Preuilly.
There are many reasons for pollarding: to create a mop-headed tree whose leaves are protected from the reach of grazing animals, allowing the tree to act like a raised coppice; conversely, to provide fodder from the prunings for beasts; to provide a regular supply of manageable sized wood for heating, forges, ovens and charcoal; to provide wood of a specific size and shape for ship or roof building; to manage fruiting trees like olives, apples and chestnuts so they are a convenient size for picking and have an increased yield; to create stems or small branches for specific uses such as basket making, stakes and tool handles; to limit the growth of a tree in a confined space, either in a managed forest or in an urban situation. After repeated cuttings the tree develops a calloused top to the trunk, which bulges and twists to resemble a gurning face (which is what 'trogne' actually means). The practice is ancient and widespread.
A pollarded mulberry in the Parc floral de Paris.
One of the best sites in Britain for seeing ancient pollards is Hatfield Forest, where the Hornbeams Carpinus are particularly impressive. Curiously, Hornbeam is rarely pollarded in France. In the Marais Verte area of Poitou-Charentes, to the west of us, the drainage ditches are lined with pollarded Ash Fraxinus. In many areas the prunings from Ash pollards are used as fodder, and as the Marais Verte is traditionally used for cattle grazing (both beef and dairy), I wonder if it is used in this way here. Around Preuilly the most commonly seen pollards will be Planes Platanus (platanes) and Limes Tilia (tilleuls) used as street trees.
A row of trees at Chenonceau, pollarded so they form box shaped crowns.
According to a recent article in British Wildlife (Vol 19, No 4, April 2008) by Helen J Read, there are important consequences of pollarding and implications for nature conservation. 'One interesting effect of pollarding is that, through regular cutting, trees can reach much greater ages than uncut trees. The lifespan of Beech in Britain is generally 200-250 years, but pollarded Beech can live to over 500 years. Regular cutting also increases the range of niches, such as decay pockets, holes, small water-filled cavities, loose bark and sap runs, and these mean that the trees may have exceptional wildlife value. Birds and bats find good roost sites, and a multitude of invertebrates, such as flies and beetles, some with very specific needs and some exceptionally rare, are found in pollarded trees. Places with concentrations of old pollards may be some of the most important places for biodiversity in Europe.' She also says that 'a small group of old pollards can be more valuable than a bigger area of young woodland' but that 'many nature conservationists are failing to realise' this. Pollards are threatened because they must be maintained using traditional skills which are being lost in many places. Once a pollard has 'lapsed' any attempt to restore the system is often unsuccessful and results in the death of the tree.
The Maison Botanique in Loir et Cher, to the north of us, has a very informative website (in French) and a garden where you can visit and attend workshops.