This is an addon that I started when I found out that most nature updates didn't make the trees bigger, so I started on the "Flourishing trees" addon.

That addon has now become "Atlas: Trees" and is larger and better than I planned it to be!

The addon has redone every single biome that has trees.
Now the tree's variations grow from saplings!

What's new from the last version?

Added A new Version that has less grass than the normal version.
(There is also a compatibility version between decay and minimal grass)  
 Things to consider:

Start a new world when using this addon.

This might not work on console editions of Minecraft and weaker devices might lag and crash. 

If you are experiencing lag, turn down your simulation distance and/or render distance.
If your device is struggling trying to render leaves, turn off fancy leaves. (It's bundled with "fancy graphics" on some devices.)

Enable These experiments when making the world:

My video showcasing the addon: 
 

Very cool images of this addon.

There are many more features of this addon that are not shown in these pictures, so try it out and tell me how you like it!

My other addons "growing forests" and "growing extra" have compatibility with this addon and complements it well.

IMPORTANT:
This addon has four versions, the normal one, the one that has leaf decay enabled, the minimal grass one, and the one with both minimal grass and leaf decay enabled.
I recommend the normal one for building in trees.
With the normal version the leaves of most of the huge trees don't decay so you have to break all of the leaves on them to get rid of them.
But if you want the leaves on the massive trees to decay, you can get the decay one.
There are some side effects to interacting with trees in the decay version which will disfigure the tree and some other trees around it (if touching).
The default Minecraft decay rules can't handle the size of these trees so when it gets a block update, the leaves that are too far will decay.
The decay version also means that leaves will decay and drop their item drops on the ground. I found out this causes major lag, so it is recommended to clear out the items if you want to keep your game lag free.
 

Anyways, if you don't care about that then the decay version is there... or here.

you should be able to import both of them and test both to see what you want for your world.

If you liked this addon, check out my discord for some up-and-coming betas for the rest of the atlas project!
There are a few more addons there that you might want to apply with this addon...

discord server:  https://discord.gg/DqMeC33xCV

I would also enjoy if you subscribe (  https://www.youtube.com/channel/UCTBBaooA2wwpUhose3P4VLQ ) as I don't put my addons behind ad websites and therefore don't make money off of them.

Do not distribute (steal) this addon and give credit to me when using this addon in a video or showcase.
Contact me on my discord server or YouTube if you want to distribute a Modpack/Addonpack with this in it.
I hope you enjoy it and stay happy!
:J