Giant tree biom

Minecraft lacks fantasy bioms so this is a good place to start, There are two places to go from here so ill do 2 seperate parts. 1. A long biom with large trees about the size like a tall roofed forrest but at the center of the biom theres one massive tree that might be up too 100 blocks tall and 40 blocks wide, I imagine it being very wide and not as tall so it looks old. 2. A biom full of huge trees maybe 10 blocks wide and 50 blocks wide with lots of water pools and roots sticking up out of the ground

*If needed I could help with some basic designs of trees because im pretty good at building*