I really like Jerm's Better Leaves, but a drawback to using it is that custom trees added by mods don't get the same bushy treatment that resource pack gives to the base game's trees. The effect can be rather jarring when you stumble upon such a modded tree in the middle of a default forest or, worse yet, when a custom biome spawns a forest of modded trees with default trees sprinkled throughout. The mod's trees usually feel... just plain weird.
Seeing as I've been really digging Ars Nouveau too, I decided to fix that problem and also give the archwood trees that bushy look. I've made a new leaf block model from scratch to closely match Jerm's, drew a new texture for the bushy parts and this is the result. Archwood trees look latifoliata to me, so that's what I went for. I did not retexture the base leaves, however, and in fact this resource pack inherits the original look from Ars Nouveau itself.
To use this resource pack, you'll of course need to have Ars Nouveau installed in your game.
In case that isn't clear, this resource pack doesn't touch the base game's trees. If you want that bushy look on them, you'll want to get another resource pack to modify them. I highly recoment Jerm's solution, but there are many others that should work just as well.
Feel free to use the model from this pack in your projects - I'm sure there are other modded trees out there begging to look bushy! Be sure to credit me if you do so, though. You may use the textures as well, though I wouldn't recommend it, as things would start looking too "samey".
(If you're looking for "bushy support" for other mods, make sure to check these resource packs I made for Quark and The Underground.)