Trees can't be converted or exported because they are based on metaballs and currently metaballs cannot be converted or exported. There's a bit more work involved in converting metaballs to a mesh than booleans because of the way metaballs work.

Flak ... some insane person actually modeled a cathedral in Bryce? What were they thinking? Musta been a newbie trying to prove something to herself ... er ... themselves.

And no, I don't think they worked on the OBJ export thingy for imported OBJs, but I can't be certain.