Went to a camping in the Laurentians in Québec (Ste-Agathe) and there were those things near some camp sites. The sites are only accessible by footpaths. No car access. And if you bring a bike, you have to walk it up a hill, so I doubt they are bike racks.
EDIT: I have sent an email to the park and they have been kind enough to reply. It's just a type of fireplace with a grate. They didn't give more info than just this. Thanks to everyone for pitching in!
As a non-skiier, I need more information please!
During the winter they might groom these trails for cross country skiers. And if it's next to a table it would be a rack you can place your skis while you take a break and have a bite to eat or something