Oliver: I think you should be a bit careful calling it 'private land' as they may well be orienteering in privately owned forests.
Here are some links that might help:
'Allemansrätten gives a person the right to access, walk, cycle, ride, ski, and camp on any land—with the exception of private gardens, the immediate vicinity of a dwelling house and land under cultivation.'
http://en.wikipedia.org/wiki/Freedom_to_roam'Restricted areas are also gardens, cultivated sites, or, constructions made by the owner.'
http://www.sverigeturism.se/smorgasbord/smorgasbord/natrecsp...'For example, you must not intrude on the grounds of a house or cross cultivated ground.'
http://www.naturvardsverket.se/en/Enjoying-nature/The-Right-...