If I disable degradation, will it prevent the trees to spawn over those tiles like concrete and asphalt?

Could it be possible to also have a minimum distance between degradable tiles when degradation is disabled?

Trees will never grow on those tiles that can degrade no matter if degradation is enabled or not.

If degradation is disabled ... what would the minimum distance be for? I'm not sure what you mean here.

I mean, not having trees right next to the tile, like the uranium field...
Not having that harsh line where concrete ends and a dense forest begins. 1-2 tiles of nothing. Even better, progressive. 1-2 tiles of nothing, then 1-2 tiles with some trees and then, yes, start the 'forest'

This is even more interesting when you have the trees at the south side of your factory. Like... you have an assembler, south of it 1-2 tiles of concrete and then, you endup with so many trees that they end slightly covering the assembler machine, so the 'gap'

Ah ok I understand what you mean now. I've added it to my todo list thanks for the suggestion.

Unfortunately due to performance reasons I will not be checking tiles (things like concrete or stone path) to check if trees should grow near it. This is mostly due to compatibility with others mods making this check quite expensive.

However due to my latest changes something close to what you want is possible and already implemented. Now by default trees will not grow near player placed entities. By default this is a radius of 2 but you can easily set it to 8 (or more) to get more or less the same effect as uranium ore has on trees.