I recently watched a german documentary "Das geheime Leben der Bäume" [1] where they visit this exact tree. Highly recommend it. The documentary is based on a novel of the same name by the author Peter Wohlleben [2].

[1]: https://www.3sat.de/film/dokumentarfilm/das-geheime-leben-de...

[2]: https://www.amazon.de/Hidden-Life-Trees-Communicate-Discover...