To make deforestation something to take into consideration, and also for realism purposes, I think the bottom of trees should stay rooted to the block they grew on, and disappear over a long period of time. Also, trees should grow a lot slower
The most of this features are already added on dynamic trees mod.
Mod that is actually really cool and love how it works!
- You can fertilize the tree
- You can break a branch and its still growing.
- You can take of some leaves, without damaging the tree