The Radio Oak

Photo taken by Holger Ellgaard and downloaded from: http://sv.wikipedia.org/wiki/TV-eken

The Radio Oak (called Radioeken or TV-eken in Sweden) was a huge veteran Common Oak (Quercus robur) growing in Södermalm in Stockholm. It was estimated to be in excess of 400 years when it was felled in late November 2011. The felling generated strong feelings including a peaceful occupation of the tree and death threats aimed at the crane operator involved in the felling. I never saw the tree, but some professionals who did consider the decision to fell unnecessary.

Prior to felling, the tree had a stem girth of almost 6 metres, a height of 16 metres, and an average crown spread of 20 metres. Typically for an Oak of this age it hosted a number of fungi, including Laetiporus sulphureus, Fistulina hepatica and maybe Daedalea quercina.

What is particularly interesting for arborists is the tree’s reaction to a construction event. The entire root system was buried in at least 2 metres of fill sometime in the mid to late 1950’s. A small gap appears to have been left around the stem; maybe covered with wooden boards to prevent people falling in…

1957. Photo taken by Georg Assarsson and downloaded from: http://www.dn.se/blogg/epstein/2011/12/02/skansenakvariets-chef-forvanad-over-tv-ekens-friska-grenar/

A sizeable city road was then built. In 1963 the tree looked like this:

  Photo taken by Ingemar Gram and downloaded from:: http://sv.wikipedia.org/wiki/TV-eken

In the early 1970s one of the three(?) primary limbs died and was removed. It is reported that around this time a concrete retaining wall was built around the submerged stem.

By 2011 a major secondary limb had died; the tree looked like this in October:

  Photo taken by Holger Ellgaard and downloaded from: http://sv.wikipedia.org/wiki/TV-eken

Assuming this last picture hasn’t been tampered with, the tree appears to me to have had pretty good vitality in 2011. An arboricultural report commissioned by Stockholm Council in November 2011 recommended felling the tree, this recommendation partly based on the assumption that the root system was by now significantly decayed. I have heard that Stockholm University have been awarded a grant to study the rooting environment.

I think this series of photos is hugely important for those interested in veteran trees, protecting trees from construction damage, and assessing trees damaged by construction activity. Some 54 years after the 2m raising of the soil profile, the tree was still very much alive and functioning. It’s certainly changed the way I will approach my assessments of trees with disturbed rooting environments, and (dare I say it?) could even be used as a reference to justify a decision to retain a damaged tree.

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