A bit of googling (and some suspect google translates) came up with this:
> It is a Finnish road 10km from the Russian border near the town of Raate, in 1941 trees were hanged above to hide it and hide the movement of the sight of a Russian observation tower nearby.
So they weren’t trying to make it invisible to aircraft.
Makes me wonder how effective that was. From my untrained point of view, this would only break up roads into smaller segments, and when viewed from the air would look like dashed line which I think is also easily identified