Monday 4 April 2016

The demise of the Turkey Oak on the Plantation



The great and distinctive Turkey Oak on the Plantation in the middle of Woodbury Salterton was recently found to have progressive internal fungal rot.  Unfortunately in this condition it presented a danger to the public, especially as it was growing on the edge of Village Road - so, with sadness and regret, the Parish Council decided it needed to be felled.  The work was done in sections over two days, 9th and 10th of February, by skilled tree surgeons from local company Ace Arboriculture - with Parish Tree Warden Sally Elliott standing by to make this visual record.  

Further below we present more information about Turkey Oaks in general, and this one in particular - including an interesting assessment of its age, and its possible relation to the development of the Plantation as a village open space.








Turkey Oaks (Quercus cerrisare vigorous, fast-growing, strong, and tall - potentially reaching 40m high.  They are not native, but were introduced from the Balkans and Turkey in the 18th century.  At that time they were well-regarded as ornamental parkland trees (of which this one was a fine example).  They were also expected to be valuable for construction, but were later discovered to split and warp when seasoned, and so were relegated to use for fencing and firewood.

Turkey Oaks were widely planted in this country and began to naturalise: the first one recorded in the wild was in 1905.  Since then there has been a large increase in numbers, and they have aggressively colonised more sandy soils, to the detriment of native plants.  In Europe they are extensively naturalised, and appreciated for their fast growth.  

Most cultures in Europe also regarded these trees highly because (like oaks in general) they were considered sacred to many gods, including Zeus (Ancient Greek), Jupiter (Roman), and Dagda (Celtic) - each of whom ruled over thunder and lightning.  

The trunks of Turkey Oaks are long, straight and grey, with various plates and fissures forming as they mature.  Orange-coloured fissures near the base of the trunk are a distinctive feature.  The wind-pollinated catkins are a source of pollen for bees and other insects.  The acorns are large and round, orange towards the base with a green-brown cup.  They are densely covered in soft, long, mossy bristles, which are especially conspicuous in winter.  The acorns are very bitter, but are eaten by jays and pigeons.  Squirrels usually only eat them when other food sources have run out.

Image sourced from Wikipedia

The leaves are distinguishable from native oaks by being narrow, with variable pointed lobes and deep cuts close to the midrib.  


Images sourced from Wikipedia

The tree hosts the knopper gall wasp, and acorns may often be found with a single exit hole in them.  The larvae provide early food for birds, but unfortunately they damage the acorns of native English Oaks (Quercus robur). 

The Turkey Oak is useful as stock for numerous cultivars to be grafted onto.  Notable among these is the locally developed Lucombe Oak (Lucombeana), raised by William Lucombe in his Exeter nursery from the 1760's, and widely planted throughout Devon.  It also hybridises with Cork Oak, producing a medium to large semi-evergreen tree, with less thick bark than the latter.  

The Woodbury Salterton tree had puzzled Sally for quite a while, since its leaf-shapes were so variable, and for a long time she thought it was a Lucombe oak.  A few weeks before the tree was felled, she picked this sample and saw that the leaves seemed to be of both Turkey and Lucombe oak!


Note the variation in the leaf shapes on a single twig

We are very grateful to the tree surgeon, Sean Ficken, for explaining this phenomenon:

"I would say that looking at the leaves in the picture it's probably Turkey Oak.  However, Turkey Oaks and Lucombe Oaks are very difficult to tell apart.  There are two types of Lucombe, type A and B.  The type A's are normally more common around our area and probably traced back from the original plants in around 1762.  In my experience I've noticed that Lucombe Oaks have a smaller, more squat form and longer boughs, and as long as the winter is not too harsh they remain virtually evergreen.  By contrast the Turkey Oak is tall and gun-barrel straight.

"True Lucombe Oaks (Quercus x hispanica 'Lucombeana') are clones of the original tree, but the term 'Lucombe Oak' is also often used to refer to any hybrid between Turkey Oak and Cork Oak (Quercus suber), and there are many different hybrids.  The more lobed leaf could be seen as similar to a Quercus x hispanica 'Diversefolia.'  

"But it could also very easily be a leaf from a 'Lamass growth flush,' which in itself is a very interesting phenomenon of oak trees.  Oaks have basically evolved over time to produce a secondary show of leaves in the summer - as you will find that a lot of the leaf-chewing insects such as tortrix viridana (leaf roller) lay their eggs on buds and hatch at the same time as the buds emerge into leaf, then strip the tree of its leaves!"



The black markings on the stump are known as pseudosclerotial plates.  They are formed by the tree as a defence mechanism against disease, and are an interaction zone or battle line between sound and diseased wood.  Sean said, "Wood-turners like them, as long as the timber hasn't degraded too much; they regard it as spalting." 

He also explained that, "The top sections of the main stem showed that at one time the tree used to have two co-dominant leaders.  This simply means that the main stem split into two, but from the cross sections of timber the two stems were growing too close together, making them 'included.'  At some time, one of these stems has failed, leaving the other to become the dominant main leader.  Over the years this has been hidden away within the annual rings that the tree puts on whilst it grows." 

The tree was about 70m (55ft) tall and initially thought to be about 120 years old, but Sean continued, "I would say from looking at the stump that the tree was quite a bit older than first thought - maybe 160/170 years old."  He concluded somewhat lyrically, "As an arborist it is very interesting for me to examine the cross-sections of old timber, as it can give a year by year account of what was happening at that time, through the Great Wars etc ....  They are indeed the silent scrap books of time.  Very interesting to know what that tree must have seen over its life span."

His dating of the tree is intriguing as it suggests that it could have been planted at the same time as the well-house/water-conduit on the Plantation was built and given to the village by local benefactor Miss Marianne Pidsley of Greendale House in 1847.  This was also the year of her death, almost 170 years ago, so there is a possibility our Turkey Oak was part of her memorial.  It was certainly a handsome tree - part of local life since the mid-nineteenth century - and its demise leaves a gap in the village scene.