Tree lighting problems

I have a problem with lighting the tree so they look realistic because if I light the terrain/objects corectly then the 3dmesh trees are to dark and the bilboard trees too bright(see the picture. The close tree are realy dark, not all of them thought. The trees in the distance is almost completly white)

But if I light the 3d mesh trees correctly then everything else is to bright and if I try to set the lighting to fit the billboards the oposit happens. I've tried adjusting the textures but it didn't help and I've tried disableing tree AO and that didn't help.

Is there some way to adjust brightness of the trees or is there any other fix for this?