Put some poly-fil quilt batting around the base. It will look like snow.
I think you may be able to buy it by the foot at the craft store.
I think that is what I actually bought to use for “fake snow”... I’m not crafty at all...but it was some kind of quilt filler or pillow stuffing. Amazing how good it looks with a few items placed on it. Good thing is you don’t have to cut or measure anything. Just pile it under the tree. Pets love it :)