The Trsteno Planes – largest trees of Europe?
At the second European Champion Tree Forum, October 2011 in Bonn, Germany, two of the participants, the tree experts Aubrey Fennell of Ireland and Jeroen Pater from the Netherlands were talking about a huge Oriental Plane tree (Platanus orientalis) in Trsteno, near Dubrovnik, Croatia. They thought that it could be the tree with the largest wood volume in Europe, larger even than the great Oak of Ivenack in Germany, which was thought to be at least the largest tree in Northern Europe.
Jeroen Philippona had heard this and received measurements from Mr Fennell, who had visited the tree in 2005. With a hypsometer he had measured a height of 44 m and a cbh of around 12 m. He thought that the tree could have a volume of 150 to 200 cubic metres. A second plane tree beside it is nearly as large.
When planning our trip to the Balkans we decided to visit these Trsteno planes. We emailed the Dubrovnik Municipality, who own the trees, and with our references received permission to climb and measure the largest tree. On June 22 we arrived in Trsteno and met Nikolina Đangradović and Ivo Stanović, two officials of the Dubrovnik municipality.
As we admired the trees they gave us some information about their history, which centres around the tree nearest to the road, the largest of the two.
It is thought that in the early 16th century a Diplomat from Constantinople brought 5 young plane trees as a present which were planted near a spring in Trsteno and of which two have survived.
In 1806 Napoleon's army were about to invade Dubrovnik but were stopped at Trsteno by a huge limb shed from the tree. The local priest managed to convince the invaders that it wasn't done to stop the army but was a limb shed by the tree many years before. It took the army 2 days to cut the limb and clear the way. In those 2 days the government of Dubrovnik were able to negotiate with Napoleon and save the city from the French invaders - the tree had saved Dubrovnik!
50 years ago someone tried to remove a hornet nest in the hollow trunk by setting fire to it. It took the fire brigade an entire day to put out the blaze. According to Ivo part of the water entered the heart of the tree and damaged it.
20 years ago a car came off the road and crashed into the trunk. The car was wrecked and the 1 metre scar on the trunk is still there.
5 years ago a huge limb fell off and killed a French tourist. The plot was fenced off and 2 years later the crown was reduced by around 25% by a team lead by the German expert Bodo Siegert. According to Siegert the tree was originally 48.5 m tall and after the pruning just over 42 m, both measured by climbing with tape (with laser we could measure only 40.7 m at maximum, so we hesitate to trust the original figure). He thought the tree could have a volume of 200 to 250 m3!
A sonar study was done a couple of years ago on the limbs (but not the trunk as it is too large for sonar to penetrate). There are hollow spaces in the large limbs thought to have been caused by a fungus. There is blight on the leaves too. According to Siegert a lack of funds prevented other urgent soil and water situational measures from being carried out.
The second of the two huge Trsteno planes stands in a walled garden on the east side of the larger tree. Between the trees is a spring which has given the trees the possibility to grow to gigantic dimensions. Ivo Stanović informed us that the second tree lost a large part of its crown in high winds in 2003. Before that it was measured at 46 m tall (measuring method unknown). The tree is perhaps 10 to 20 % smaller in volume than its neighbour.
We measured the girth and height of both trees. Michael climbed the largest tree to make series of photos, which were to be sent to Michael Taylor to make a three dimensional point cloud to estimate the total volume. Michael did not climb to the top to measure the height with a tape drop.
Here are our measurements:
Height: 40.6 – 40.7 m / 133 – 133.5 ft
Circumference @ 2.0 m: 10.75 m / 35.27 ft
@ 1.5 m: 11.73 m / 38.48 ft
@ 1.3 m: 12.10 m / 39.70 ft
@ 1.0 m: 12.91 m / 42.36 ft
@ 0.5 m: 13.91 m / 45.64 ft
Crown spread: 28 – 35 m / 90 – 115 ft
Height: 33 m
Circumference @ 1.5 m: 11.39 m / 37.4 ft
@ 1.3 m: 11.54 m / 37.86 ft
Crown spread 26 – 35 m / 85 – 115 ft
Whilst we hope that with the photos Michael Taylor will be able to make a good volume estimate,
we have already made a very preliminary estimate of the wood volume:
The trunk to 15 m height could have a volume of around 100 cubic metres (3531 cubic feet), the rest of it another 10 m3. The limbs and branches could have a total volume of about 50 m3. So the total volume could be around 160 m3 = 5650 cubic feet.
The second tree could be about 130 to 140 m3 = 4500 – 5000 ft3.
Among other contenders for the largest tree in Europe that we know of are:
The Oak of Ivenack, Germany (Quercus robur) which is estimated at 120 to 140 m3 (4200 – 5000 ft3), a Sessile oak (Quercus petraea) at Croft Castle, England: estimated at 107 m3 (3800 ft3), (Robert van Pelt 2006), a few other oaks estimated at 90 – 100 m3 and several giant sequoias (Sequoiadendron giganteum) in Switzerland, Germany, France, Belgium and the UK of at least 100 – 110 m3.
Also some cedars of the Lebanon (Cedrus libani) in England, a European white fir (Abies alba) in Scotland and several European sweet chestnuts (Castanea sativa) in Spain, Italy and England have a possible total wood volume of around 100 m3. Very large oriental planes exist in Greece and Turkey, but exact volume estimates for these are not known.
The giant sequoias will, in a few decades, be the largest trees of Europe, but of Europe’s native trees the oriental plane trees of Trsteno are likely to remain the largest.
In Trsteno there is still more to see for the lover of trees. The nearby hills are full of Italian Cypresses (Cupressus sempervirens) of different shapes: very narrow ones as well as rough, broader types. Between the Plane trees and the Adriatic lies the famous and very old Trsteno Arboretum, dating from the fifteenth century, laid out as a beautiful renaissance garden with fountains, an old villa, and full of mediterranean tree species: various cypresses, palms, olive and citrus trees, Aleppo pine (Pinus halepensis), oriental hornbeam (Carpinus orientalis), downy oak (Quercus pubescens), etc.
Besides this, the views over the Adriatic and Trsteno harbour are great!
Jeroen, Michael & Kouta