So I'm working on The Pale for one of my landscape overhaul mods and I'm currently working on remaking the Stonehills into actual Stone Hills by using pillars pulled from the cave tileset to replace the trees. The effect is really nice and it looks great, there's only one problem. The incredibly ugly tree LOD is still present and for some reason visible right up close. It looks disgustingly bad. Is there an easy solution to this problem that I'm missing? I've never had this trouble with replacing or removing objects before and I don't know why its come up now.

Any help would be greatly appreciated!

Have you already generated your tree and object LOD? There is a known game engine issue where tree LOD doesn't go away and not much you can do about it.