Fire Pit Safety - Nearby Trees

Hi everyone!

We're looking to add a fire pit to our backyard. Something simple like a fire ring (like this one http://firepitideas.net/cobraco-evening-sky-campfire-ring-frstar369/ ).

While we have plenty of clearance around the pit itself, it's what's overhead that concerns me. About 25 feet up, there are a few large tree branches sticking out directly over where we'd like the site to be.

Does anyone have thoughts about a) the likelihood of catching the tree on fire? or b) the likelihood of damaging the tree?

Thanks!