Every tree drops seeds of its own species, or the fabolous Uni-Seed if you don't like having your inventory full of various seeds.
You can plant it and when it's grown up, it gets marked for deconstruction and replanted automatically.

This is a temporary fork of Tral's Robot Tree Farm by MarcusTral that updates the mod for Factorio 2.0. Follow the link to the original work for more info.