My issue:
when the schematics origin is an air block rather than a log, the sapling stays in place. It would be really nice to see the sapling removed when it grows regardless of the schematic being placed!

My Ideas:

1. You could add biome dependent trees. For example, I would personally make jungle trees grow into a palm tree in a beach biome and regular jungle trees in the jungle biome. (and obviously, default to jungle if a biome isn't specified)
2. You could also make certain trees rarer than others. Or maybe a "strong sapling" of somesort? This would be really cool to add because I like the idea of players being able to grow MASSIVE trees, but not everyone will want to just for a tree farm. So either added an optional rarity value or special way of growing different (presumably bigger/unique, depending on settings) trees would be really cool.