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Sessile Oak is Tree of the Year 2014


Tree of the Year 2014
Sessile Oak (Quercus petraea (Matt.) Liebl.)


In 2014 we want to draw your attention to one of the indigenous tree species with the highest average life-expectancy: the sessile oak (Quercus petraea) can survive for more than a thousand years. It is an attractive species in forestry, but is also suited for cities and the open countryside. Of course, everybody is capable of recognizing an oak tree, but to tell a sessile oak from a pedunculate oak is less easy; in fact, even professionals sometimes have trouble eliminating all doubts.

Therefore let us start by asking: what are the differences between these two species of oak? Specialists agree that you need to check at least three characteristics to be sure. But which ones? You will hear different opinions on the subject – however, there is a certain amount of consensus that the following three points should be on the checklist (SO: sessile oak/ PO: pedunculate oak)

SO

PO

Veins lead to the emerginations between the lobes of the leaves

no

yes

There are tiny hairs along the main veins (use a magnifying glass!)

yes

no

The leaf petioles are more than 1cm long    

yes

no


If you check the leaves for these three characteristics, the result can score (yes to no) 3:0, 2:1, 1:2 or 0:3, the first two results voting for sessile oak, the last two for pedunculate oak. It can be helpful to add a fourth and to take a look at the fruit. That shouldn’t be a problem: you will almost always find some on the tree, ripe or unripe, or still lying on the ground from the previous autumn.

SO

PO

the stalk of the fruit is 2cm long or more, the fruit evenly distributed along the length of the stalk (if you find the fruit sitting closely together as raceme, it is a sessile oak)

no

yes

Now the score could be 2:2 – in that case it  be a hybrid.Admittedly, it is a little unsatisfying that so many characteristics are needed to tell them apart – and you will not be surprised to learn that among scientists, the question has come up whether a difference so hard to make is worth making at all?Sessile oaks can grow up to 40m high, and the biggest trees (“champion trees”) achieve a diameter of about 2m at breast height. Interestingly, many of the champion trees listed as sessile oaks in tree guidebooks are actually pedunculate oaks. According to the dendrologist databank at www.championtrees.de, Germany’s champion is a sessile oak on Peacock Island (Pfaueninsel) in south-west Berlin: its trunk has a circumference of 5.70m. Unfortunately, it has been so badly pruned that it is not a very attractive sight anymore. And 5.70m is nothing – the trunk of Europe’s biggest sessile oak has a circumference of about 14m. It stands in England, surrounded by many other ancient trees in Cowdray Park near Midhurst, Sussex. It is probably more than a thousand years old. The hollow trunk is so spacious it can host a table for ten – a unique experience, that makes you sense there is some truth to the saying that an oak takes 300 years to grow, 300 to stay and 300 to die. The acorns, which start falling from the trees in October, are highly appreciated by deer (and also, in days gone by, domestic animals sent into the woods) as they are very nutritious and – apparently – rather tasty. Every couple of years, all oak trees simultaneously grow an extraordinary amount of fruit – the so called oak mast, which once produced fat pigs, deer and domestic animals. “The best ham grows in oak”, as connoisseurs say to this day.Oak is known for its tap root, i.e. it develops a very strong main root going straight down. Thus securely anchored in the ground, it can resist even heavy storms. Sessile oak is preferentially found on dryer, less nutrient-rich ground – at least in theory. In reality, both oak species often grow on the same spot. Sand oak is closely-related to sessile oak; and the Spessart oak is said to be the “cream of German forestry” – sessile oaks in the Spessart woods have a particularly straight trunk and particularly fine wood. Oak trees are known as veritable sanctuaries for animals. Residents particularly worth seeing include the oak long-horned beetle and the rare stag beetle. No other tree provides shelter to so many animal species – up to 500 different kinds of insects choose oak trees as their homes or food, and they in turn attract many different kinds of birds who feed on them. Other birds, like the jay, feed on the acorns themselves.Humans naturally focus on the wood. It is processed in the form of log wood, sawn timber or as veneer. Due to its enormous durability, the heart wood is very popular outdoors, to make fences and posts, but it is also used for wine and whisky barrels (giving the liquid an ‘oaky taste’), for the construction of half-timbered houses, furniture (particularly for those fond of a rustic look) and panelling, as well as for windows, doors, stairs and floors. High quality veneer wood realises up to 3000 EUR per cubic metre.Oak trees have inspired more myths and legends than any other tree species in Europe, and that is easily explained by their impressive look and enormous life-span (the tales made no difference between sessile and pedunculate oak, incidentally). The wood is so durable that dead branches or whole parts of the crown often remain on the tree for decades, and then lie underneath it for another few decades. Long-dead trees sometimes remain standing for up to a hundred years. Anyone who plants an oak tree must be a real long-term planner – only the great-great-...-great-grandchildren will get to see the fully-grown tree. However, a planter’s ambitious plans do not always work out quite as expected. For example, there are oak forests in England and Sweden planted 200 years ago by royal command: the kings wanted to make sure their navy had sufficient wood to be able to build powerful warships. Those trees are now ready to be cut. The thing is, wooden warships are rather out of fashion nowadays.Of course, this wonderful wood is immensely valuable nonetheless. In any case, sessile oak is a tree of the future – not least because the predicted climate change will probably hardly affect it at all.Our annual conference takes place on Wed 4th/Thurs 5th of June 2014 in the Thuringian Forestry District Heldburg (South Thuringia), including a field trip into the surrounding sessile oak woods.For further reading, visit www.baum-des-jahres.de and www.holzgewaechse.de (in German).Translated by WiebkeRoloff

 

Baumkönigin

Miriam Symalla Baumkönigin 2014