I thought it was an odd thing to do a sculpture of, so I googled bronze oak leaf sculpture and got dozens of them, go figure, huh ? None like yours though, sorry. Will it detach from the base ? Maybe there's a makers mark underneath.
If the bronze is bolted to wood stand can you take it off and see if there is any info underneath ? Looks like a nice bronze and could have been an award or something and someone removed the plaque so it would be just a nice piece of decor?