Management of lapsed and new pollards

Ted Green presentó a las primeras jornadas sobre los árboles trasmochos celebradas en Calamocha en 2010 un artículo sobre "Management of lapsed and new pollards". Se puede descargar la presentación en PDF.

 

Cork oaks in Extramadura are an example of centuries old cultural tradition of cutting pollards.


There are also examples of ‘trasmuchos’ in the UK. These are now massive old lapsed pollards. Past term for this type of tree is - ‘compass’ tree. Compass means curved – trees planted and trained for future use for building of houses and ships. There are still kilometres of these pollards or ‘trasmuchos’ in the Basque country. There were many different uses for the products from these trees down the centuries – one use taking over from the other as technology moved on. They were originally cut for the shaped limbs for building or ship building but then it became possible to bend wood under steam. So they cut the limbs to make charcoal to heat water for steam. Then they cut them for charcoal for iron/ steel production. Now they are valuable for their cultural heritage and biodiversity values. Beech pollards could be shaped for a purpose. These ‘orchards’ of pollards are in Basque Spain – in Aiako Harria Natural Park south of San Sebastian. There are now concerns over regeneration of these trees, however it is important that we do not cut down trees to make gaps for regeneration. It is necessary to get regeneration around the outside of these areas. In the UK we have very many, very old pollards that we now call ‘lapsed’ because it is a long time since they were last cut in rotation. The limbs on these trees are very large and our major concern is that trees collapse under their own weight. Hence the need to intervene to lighten the crown to prevent catastrophic collapse. We cannot afford to allow any of these trees to collapse in this way – we wish to see no further avoidable loss of ancient trees. In the UK, originally we tried cutting ancient, lapsed, oak pollards back to the original cuts or ‘bolling’. However, the cutting of this size, age and diameter of branch resulted in killing many of the trees. The same happened with old lapsed hornbeam (Carpinus). Members of the Ancient Tree Forum started to meet at different sites to discuss why trees were dying and how they could be managed better. This is the Ancient Tree Forum having a discussion under an ancient oak – I call this 50 brains working together to come up with good solutions. There is so little written down about the tradition of pollarding and nothing about how to care for lapsed pollards. So we have to learn everything for ourselves. We also look at old paintings to see if we could learn about old techniques. This one is full of pollards and shreds in Romania. Each one of the trees in this picture has been cut for different products. And we can look at old tapestries to see cut or pollarded trees. We can even compare old drawings and paintings with the trees today. This example is comparing a drawing of 1815 with the same tree today. Remarkably this tree seems to have grown very little in nearly 200 years. These examples give us an insight into how ancient trees change over time. A diagram showing the process of how trees grow and become ancient – the changes to the shape of the crown and due to hollowing. Shown from the side and in cross section of the trunk. Note the stag heading as the tree goes beyond the mature stage and a new crown is created lower down. Retaining dead and decaying wood in the crown is very important. We looked in the countryside for examples of trees ‘growing downwards’ (crowns reducing in size/height) as they age and their responses to high winds which are frequent in the UK. Here is a stag – headed oak tree that has started to grow down. In this case the cause of the loss of the upper crown is probably due to a long drought. A natural example of a tree recovering from the impact of a very high wind. One part of the old crown remains and a second very vigorous crown is developing on the other side. In this case all the major limbs except one of the tree were reduced by a high wind. The tree has responded by creating a perfect new crown. This sort of example gave people the idea to try ripping limbs or break out limbs to naturally mimic crown reduction by wind. An open grown beech that hasn’t responded as well as all the previous oak trees. This made us consider the responses of different species of tree to wind and the aging process. We are still unable to explain how trees respond to leaf fall in autumn. In the case of this mature beech tree, it has developed two ‘crowns’ – the top one has lost all its leaves already. Can this help us decide where to cut trees when we want to reduce them as naturally as possible? Even younger trees such as this hornbeam (Carpinus) may produce two crowns in some circumstances. The following sequence of pictures shows recommended practice in tree management in the UK. In this case a mature oak has had its crown reduced by approximately 2-3m, reducing wind resistance very significantly. Look at the size of the diameter of the cuts limbs – the cut ends are less than 15cms which is important in the first phase of cutting on some species. This is the response of the tree a few years later – in summer. Note that there has been very good regrowth, particularly lower down on the limbs and trunk. At this stage the tree could be considered for further reduction as the living wood all the way down the tree to the roots is being kept working. The same tree in winter – showing response. Because of the significant response at the end of the limbs, further intervention will be necessary before this re-growth shades out lower growth and makes the limb vulnerable to wind again. In high use, urban areas, crown management may save trees. These two oaks were threatened with complete felling and removal but tree work meant they could be retained. Ancient beech pollard that has had the first phase of tree retrenchment pruning, however in the case of poplars the first restoration cutting could be lower down. Each tree because of its species, age, condition and location needs to be treated individually. Two Examples of crown reduction of old, hollow elms near Madrid. Parallel thought in tree management by two nations. In the same town. We use this as an example to many arborists in the UK. It shows crown reduction so that an important hollow tree can be retained in a very public place. Behind the statue of Queen Elizabeth II are 250 year old Tilia that were reduced by two metres so that they could be retained. Tree surgeons undertaking phase 1 retrenchment cutting of the crown of an old oak pollard. They are cutting with hand tools half way through small branches and tearing off the remainder to mimic natural pruning by wind. Beaver coppicing. Beavers evolved with coppice. They leave stub ends and sap risers. We should mimic their methods when coppicing or we increase the risk of the coppice failing. The right hand coppice stool is a good example of leaving sap risers – in other words not taking all the stems at one time. This diagram from a French research study shows the location of starch storage when a tree is cut. The darker the shading the higher the starch reserves. It supports the reason why beavers leave stub ends - because the starch is stored near to the cut ends ready for utilisation in spring growth. Restoration cutting of an old, pollard hornbeam (carpinus) pollard. Stub ends have been left and sap risers. Where limbs are less than 15cms in diameter leave stub ends that are 6 x the diameter of the limb being cut. Hornbeam is one of the species of tree that usually responds successfully to cutting so in theory can be reduced further than other species at the first retrenchment cut. However trees must have sufficient light around them in order to respond effectively. Two illustrations of an ash that has been cut in Spain on a regular, short rotation by axe. Where cutting is done by axe on a very regular basis and no lapse in the cycle, the trees appear to live very long lives – longer perhaps than maiden trees. Close up of the cutting which was done by axe. Traditional, 60 year rotation cutting of beech pollards in Leitza, Navarra by a local woodsman. In the Basque mountains, the climate is cool and the rainfall is very high. Presumably these conditions allow the cutting of larger limbs. This degree of cutting in the east of England would kill similar trees because of the low rainfall. A series of illustrations of Black Poplar pollards that have been cut leaving sap risers. It was in this region, 30 years ago, that the Ancient Tree Forum saw this practice for the first time. Sap risers and abundant re-growth on an old pollard. Black poplar in the Sierra Guadarama where the practice of leaving sap risers on old trees was first seen in the 1970’s. Trees that produce wispy epicormic (shoots) growth, like on these old beech trees on very old common land, are more likely to respond to cutting. Man may have recognised such trees that could be cut and grow again readily and successfully for long term cropping. Whiskery beech on an old iron age, hill top fort – maybe the practice of cutting has been perpetuated down the centuries. Shading by ivy or other creepers or moss, can prevent the shooting of dormant or adventitious buds on pollards after cutting and can lead to the death of the tree. The living sap wood rings of this tree have recently died after cutting and are being decayed by endophytic (dormant inside the living wood) fungi that are activated once the wood has become dysfunctional. A column of dysfunctional wood created by the cutting of a very large old limb on this ancient beech pollard is being decayed by an endophytic fungus. Comparison of two limbs on the same tree following different types of cutting. Sap risers keep the living columns in the sapwood working to the benefit of new growth in the crown and root system. The growth on the right hand side has new branches that are knitted into the stem and will not break out easily. By contrast the new branches on the hollow stem on the left have no support from the thin ring of sapwood. The left hand limb is of such an age and diameter that it may have too little living sapwood to provide the strength to support regrowth and cannot form a bolling. If we are starting new pollards, is this the age at which to make the first cut and just above the stem that retains its leaves? In the UK we are learning about starting new pollards. We believe that they should be when the trunk and limbs are less than 4cm diameter and to the form of the tree. The second cut above the bolling on a young ash pollard to continue the rotation. On this occasion the limbs below the bolling are also removed to prevent competition. Second cut immediately after cutting. Leaving stub ends, mimicking what we have learnt from Spain. Close up of regrowth after third rotation cut. Regrowth has been successful all round the cut stubs and all the new growth has knitted in well into the stem. All nations have thousands of kilometres of autoroutes that have been ‘landscaped’ and planted with trees and shrubs. We say ‘trees with no future’ because when they reach a certain size they are cut down. We believe there is a great opportunity to cut the trees to produce the different, local forms of age-old, cultural traditional practice and provide some sustainable products at the same time. Prince Charles starting new willow pollards. If we are able to inspire our future king to cut his trees in this traditional way, let us hope we can persuade others across Europe to help preserve part of Europe’s cultural heritage. It took 9 members of the Ancient Tree Forum with outstretched arms to encircle the trunk of the Bowthorpe Oak – one of the oldest oaks on the planet. The ATF is a group of people from many walks of life that are passionate about old trees and the part they play in our cultural history. Come and join us! Interview on Spanish TV.

Ancient trees and pollards. Securing their future


Conferencia sobre los Arboles Milenarios y trasmochos presentada por Jill Butler a las I Jornadas sobre árboles trasmochos celebradas en Calamocha en el año 2010. Se puede descargar la presentación en PDF.

The UK probably has more very ancient trees than other countries in Northern Europe. What are ancient trees? They are trees that as they have aged have become fatter in girth, shorter in height and hollow. Different species can live for different lengths of time and the ancient period of their lives can vary from decades to many centuries. Oaks and Yews are some of the oldest trees in Europe. We are learning more about them all the time and maybe in the 21st century we will start to fill the gaps in our knowledge about old trees and change attitudes to younger trees and how to care for them.

A brief story of pollards and ancient trees in the UK

In the UK we have had, in the past, a rich tradition of pollarding. We have evidence that the history of pollarding in the UK is very old, therefore this tradition is also of great significance for our European heritage and how past use may make a resurgence in the future. London is circled by areas of pollarded trees – these places provided wood fuel for the bakers of the growing city, especially hornbeams, because their wood was prized for making the best bread. Ancient wooded pastures comprise a mosaic of very open woodland, small groups of trees, scrub, individual open-canopied trees and patches of open grassland. The history of such sites is linked to deer and the value placed on them as status symbols by the aristocracy of Europe. The Kings of Europe protected key concentrations of ancient trees as a by product of 1000 year old Forest Law. In these wooded pastures or parklands the tree species is often very varied, however typically there are large, old trees present such as oak Quercus robur, ash Fraxinus excelsior, beech Fagus sylvatica in pastures with a long continuity of grazing.

In the UK we have a very special heritage of old trees. William the Conqueror 1066-1087 because he loved hunting had a lasting impact on our landscapes and our rich inheritance of old trees that we can see clearly today. He and the Mediaeval Kings brought Forest Law to protect grazing and deer and did much to support commons and commoners rights. The Tudor kings brought in the first tree protection legislation to protect trees that were necessary for going to war. Historians have overlooked the significance of trees and especially pollards and tree crown cutting in old documents. In the Bayeux Tapestry which tells the story of William the Conquerors conquest of Britain they describe the treework in the tapestry as felling to make the boats, but there are no felled trees. These trees are instead being pollarded to take and use the branch wood. Sub-fossil pollards have been recently dug up out of the gravel beds of the River Trent in the Midlands of England. They are oak and have been carbon dated as 3400 years old. It is easy to compare them with old dead pollards found today. Another sub-fossil has been dug up from the gravels of the River Meuse or Mass, the major European river that flows through Belgium and the Netherlands to the North Sea, and re-erected on the banks as evidence. They can be compared with typical hedgerow pollards in France. This is evidence of a very old tradition of cutting tree to provide essential everyday materials and products for people – rich and poor.

Our Europe-wide heritage of pollarding stretches from Portugal in the west to at least Turkey in the east. In places like this tens of species new to science are being discovered. We have yet to fully explore their value for history, culture and biodiversity. It is urgent that we raise awareness of their value before these areas are cleared for intensive forestry or agriculture. The cutting of pollards also stretches from Scandinavia in the North to the great dehesas of Extramadura and the Mediterranean where hundreds of square kilometres give us examples of ‘Two tier’ agriculture or silvopastoralism or agro-forestry – trees combined with grazing or cultivation. This tradition stretches across alpine Europe to Romania and the Black Sea. And there are very individual landscapes such as these along river valleys with Black poplar pollards in Teruel region of Spain. Cutting took place of not just deciduous trees but conifers. They are all part of the picture that we are building of this European tree cutting heritage. We know now that trees have been cut in many different traditional ways for different reasons and products. There is a special terminology that goes with the different forms and styles of cutting. Much of this old language is dying out. The trees help create beautiful, historic landscapes that we believe our ancestors valued and appreciated for their beauty as much as we do today as well as for their well being.

Past recognition of the aesthetic value of ancient trees and pollards

Many old masters have images of ancient trees, old pollards and fallen decaying wood. This was especially popular during the Romantic period in the 18th and 19th centuries.

Biodiversity significance of ancient trees and pollards

As well as their importance as records of cultural traditions that have lasted for thousands of years, these old trees carry with them other species through time. As trees age they change and provide different habitats for different creatures – as old trees are rare the species associated with them are rarer still. The most special species associated with old trees are the fungi that decay the wood and are associated with the roots as mycorrhizal fungi, the invertebrates living on the decaying wood and the lichens that live on old bark. Other species such as birds, bats, other mammals and reptiles take advantage of the cavities and hollows that are created as trees age. We are still finding species new to the UK in our concentrations of ancient trees and discovering more trees with associated Natura 2000 species. In the UK the Natura 2000 species that are relevant to these trees are a couple of species of saproxylic beetles as there is a serious omission in the Habitats Directive annex which does not include any fungi or lichens –some of the most characteristic and specialised species of ancient trees.

Old trees are important in their own right because of their age

Most ancient trees are very special because they are so old and are the oldest examples of their species. For example yews hanging on a limestone cliff face have been recently discovered and are thought to be over 2 thousand years old and started life when the Romans occupied England.

Securing a future for ancient and historic trees

We, two non-government organisations, the Woodland Trust and the Ancient Tree Forum are lobbying in the UK and the EU to secure a future for our ancient trees, our ‘working’ trees or pollards and the landscapes that they have been part of for thousands of years. We are trying to raise awareness of their significance, trying to raise standards of management of old trees so they can live long lives and we want to map them so that we can quantify the resource. Why is this priority? Because there is good evidence In the UK that we have lost so many in recent times. In the UK our characteristic hedges and stone walls forming land and field boundaries are being removed or disappearing because of neglect. In the past 150 years the tradition of pollards in hedgerows has almost died out in the UK and can only be glimpsed in a very few locations. The map shows an area of Yorkshire and all the red circles with crosses are pollards that were marked on old maps that are no longer present today. A scatter of old oak pollards that is all that is left. Our recent research has also shown that Trees outside Woodland (TOWs) can represent the equivalent of 7% canopy land cover in some lowland parts of England. So loss of these trees will have great implications for society.

The Ancient Tree Hunt – mapping our ancient trees and pollards.

At least since Shakespeare people have been interested in ancient trees. Great tree hunting is part of a roughly 340 year old historic tradition started by Charles II whose life and the lives of two friends fleeing with him, was saved by a hollow pollard. Charles II sent out John Evelyn in the 1660s to learn more about the state of the nation’s trees and therefore a key resource for going to war. At the back of the report that Evelyn wrote was the first list of the greatest trees of England. Evelyn is believed to have planted sweet chestnuts at Greenwich Park in London – which will feature in the 2012 London Olympics.

Ancient Tree Hunt is about following this tradition and putting the UK’s ancient Trees – our living heritage on the map, bringing a living database of over 100,000 trees to life. Each, individual tree is recorded and located on detailed maps. Each tree is verified and for the majority of trees there are pictures to illustrate the tree on line. We now have 70,000 trees on our database collected by ordinary people and specialist surveys and this is just the start. The small remnants of pollard hedgerow in Belgium are now so rare and special that they are protected by national legislation. The historic system of oak trees providing natural fertilisation and wood fuel supported the cereal fields. Despite the poor quality of the soil, this village was able to export bread to local towns. Management of lapsed pollards (trees that have not been cut in a very long time and are top heavy) may be necessary to stop them catastrophically collapsing. Such work needs to be thought through carefully to make sure that the intervention is correct for the tree and is as cost effective as possible. We aspire to learning about and giving best practice management advice in the care of old trees.

Back to the future: a role for pollards in sustainable agro-forestry landscapes of the future.

In Norway, research has shown that greater productivity is generated in fields with pollard trees (agro-forestry) than in fields without trees fertilised by manmade fertilisers. And in addition every few years there is a product from the trees in fodder and in wood fuel. Are we watching the end of an era of custom and tradition? Is our European heritage of cutting trees no longer of value in modern society? Will scenes like drying fodder on trees in Turkey never be seen again in most places where once they were widespread? Or will there be renewed interest in the value of such trees? In the UK there is a growing interest in the nutritional value of meat that is produced through more natural grazing on grass pastures. It is clear that animals can tell us a lot about what they prefer if they are given the chance. Given half a chance many animals prefer leaf fodder particularly at certain times of the year. Cattle can be seen picking out the leaves with the most green spots left on them. These spots are caused by fungi that draw in nutrients from the rest of the leaf into their living area. The phenomenon of fungi keeping parts of the leaf alive can be seenon many different types of leaf. There is growing awareness of the nutritional value of leaves and their potential to fertilize soils.

Two old pollard sallow (salix) trees close to an old animal enclosure. Sallow is known to have medicinal benefits and we know that animals will self medicate themselves on sallow leaves and twigs. So there are great benefits to man and stock from such trees – aspects that we are only just putting together. Plantations of deciduous trees are being looked at for production of fodder and wood fuel. Also the most modern of agro-forestry experts are creating demonstrations of potential agro forestry systems formed by alleys of trees with grazing or arable cultivation between the rows. The distances between rows have been researched and 20m is the best for the benefits from the trees without too much loss of cultivated area. Trees give shelter and nutrients and can be cut for short rotation coppice or timber or planted as fruit trees or pollards for wood fuel. In the UK we know that we need to plant many more trees as we are one of the least wooded countries in Europe. As an alternative to woodland planting we could replace lost hedges or replace post and wire fences with traditional hedges and trees. This would bring enormous benefits to sustainable farming without loss of crop able or grazing area. It would look very attractive and sequester carbon. In the last few years this astonishing pollard has been found within the city of London. Our ancient trees and pollards are magnificent. We the ATF and the Woodland Trust believe that their future should be safer than it is at present.

Paisajes rurales de Flandes Occidental

 

 

 

Bélgica es un país de modesta extensión pero compleja organización territorial, consecuencia de su diversidad cultural y su dilatada historia. Se divide en tres regiones principales. Valonia, al sur, es la que incluye a las comunidades de habla francesa, aunque una pequeña parte habla alemán. Flandes, en la costa, es aquella en la que el idioma es el flamenco, variante del holandés. Entre una y otra, Bruselas, mantiene un estatus de capital con el bilingüismo como norma.
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