perhaps a mod conflict, but at some point I managed to find in my inventory 2 seeds, that I quickly converted to saplings.

For the rest, I have harvested a ton of trees and get nothing!
perhaps a recipe to convert wood to seeds would also be a plus, in case of mod conflict, at least this would work.

You only get seeds from living trees. Those trees needs to have their name start with "tree-" in the code. If it's a mod and it handles trees differently then I need to add a special case. Can you give me more informations about your loaded mods ?

I'm using Alien Biomes, a very nice and popular mod. Many new trees, I guess they don't start with 'tree'

I'll see what I can do. I don't promise there will be a fix in the next version though.

Given how popular is alien biome, this will be important for the success of your mod...

Im working on it...

is this working with Alien Biomes yet?

Sorry I kinda gave up on factorio around the time of my last comment, but if this is requested again I might just work on it.