Six hundred year old Czech tree reveals secrets

Plešné lake, photo: Miloš Turek

Czech scientists researching forests in Šumava National Park in the south of the country have recently discovered what is believed to be the Czech Republic’s oldest tree. The spruce, found near the lake of Plešné, witnessed the reign of Charles IV as a sapling, and is believed to have reached more than 600 years of age.

Plešné lake, photo: Miloš Turek
Šumava National Park, a vast stretch of pristine forests running along the south-western border with Austria and Germany, has been protected since the early 1960s and a nature reserve has existed there since 1991.

While most monoculture forests in the Czech Republic have been artificially planted, a large part of the spruce forests in the Šumava Mountains grew there for ages without any human intervention.

To this day, you can find areas of untouched nature within the park, such as the Boubín virgin forest or Plešné Lake, one of the park’s several glacial lakes located at the footpath of Plechý, the highest peak in the Šumava Mountains.

For over ten years, scientists from Mendel University in Brno have been studying the area at the Plešné lake, a valley formed by glacial erosion, focusing on the age structure of the upper level of a spruce forest that died out in the 1990s. At the end of June, they came across a spruce which that turned out to be more than 600 years old.

They cut out a segment of the trunk, which had only 60 centimetres in diameter, to find its exact age and discover more about the tree’s history. Tomáš Koutecký is one of the scientists taking part in the research:

“We learned that the tree had 623 rings, the first dating to the year 1372 and the last one to 1994, when the tree died. We also discovered that the tree rings were very narrow, only about half a millimetre, which shows that the tree grew very slowly and was probably stressed out throughout most of its life. It was overshadowed by other trees and it was also limited by the conditions in which it grew.”

Tomáš Koutecký, photo: archive of Mendel University in Brno
The narrowest rings were less than a millimetre in thickness, showing that the tree had to fight for its life as a sapling, while the thickest rings, which were up to 1.6 millimetres, came from the 18th century, when the tree had outgrown its colleagues and enjoyed more of the sunlight.

Despite the harsh conditions in the glacial valley, scientists found an unusual number of old trees in the area. From over 200 samples that they collected on the stony slopes of Plechý Hill, scientists found seven trees that were over 500 years old.

According to Tomáš Koutecký, that is uncommon not only for the region of Šumava but for the whole region of Central Europe. Most spruce trees die during their first years due to the unfavourable climate or rivalry from nearby vegetation and even if they do reach the sunlight, they have to battle wind, drought and other extreme conditions.

So how come that the trees in Plešné live to see such an old age?

“It is probably due to a combination of several factors. One is definitely the fact that this glacial valley is well protected against strong winds, so the trees grow in specific micro-climate conditions. Also, the trees were not that disturbed by winds and by bark beetles, because it is too cold for the beetle to survive. These are the main reasons.”

According to Tomáš Koutecký, the aim of the research carried out in the area of Plešné Lake is to save valuable information hidden in the trees, before their wood falls apart. One of the goals is to find out if the trees in the valley had developed in a different way than in other areas of the Šumava National Park, such as on the mountain ridge.

Plechý Hill, photo: Miloš Turek
“This kind of information gives us a better understanding of how spruce trees grow in such extreme locations and compare their development with trees from other areas. We discovered that the forest develops more or less the same. However, the effects of the climate are not as strong here.

“Unlike on the mountain ridge, the forest at Plešné has not died out completely, and new trees keep growing underneath the dead canopy. This helps us understand what will happen in the future. It is likely that trees of around 500 years of age will still be growing here.”

But the information is useful in many other ways. For decades, the Šumava National Park has been battling with the devastating effects of bark beetles. Thousands of trees in the affected area have been felled as a result, which has been the subject of considerable debate and protests. But according to Tomáš Koutecký, the research shows that natural disasters such as bark beetle infestation or strong wind have always been part of forest life and there is no need to intervene:

“We found out on the basis of our research that a disaster happens on the mountain ridge, such as Šumava, every 50 or 70 years. The only exception was the 20th century, when there was a longer pause and there was no natural disaster. We don’t know why it happened, but it was probably just a coincidence.”

As a result of this pause, people forgot about the consequences brought by natural disasters such as bark beetle calamities or gales. When a large area of the forest in the Šumava National Park suddenly died in the 1990s, the park management started to panic. But, as Tomáš Koutecký stresses, the forest has a natural capacity to regenerate.

Photo: Jan Rosenauer
“Such huge natural disasters have always been here and they are likely to return in the future. So if we want to have a National Park, we have to come to terms with the fact that this is what the forest works like, and let it deal with problems on its own, without our intervention.”

The team of scientists of Mendel University in Brno want to continue with their research of forests in other locations of Šumava National Park, such as the original glacial lakes Prášilské and Laka. So there is still a possibility that an even older sibling of the 600-year-old spruce will be found.