JPOG Jungle Mod is a mod made of edits to several tree models, with many having extra ferns and smaller trees next to them as well as size changes making certain trees larger. It makes the modern tree foliage much more dense. There is much more size diversity among the plants, giving a more complete jungle feel. This mod only changes models not textures, so it should be compatible with most mods. My foliage in the photos use JPOG Forgotten textures. This mod does not change the bubble values of the trees at all, so if you want to up the density further that is still an option for you in your own game.
This is the HD version of the mod, "Higher Density", which gives a deeper jungle feel.
The bubble values are not altered in this version either, but the tree models are more clustered. I do not recommend this for low-end computers, but if it works, then it works.
Extract the file and place all of its contents into the Models folder