Hi Matti,
thanks for feedback and revert. We can write english, if you prefer. Yes if the way ist blocked by fallen trees and hard to identify, tagging in abandoned-namespace is suitable. Thats the common approach we used also together with the user of the national park authority. The attribute 'source:Bing Aerial Images' from 2011 leads (for me) to the assumption, that there was a way visible at this time - so tagging as abandoned keeps the history of that way.
greeting, Stefan