Plant Nursery In Space?

I think the answer is in TangoMan's original post, that full sized trees are
so much productive. This is when I wish we had a botanist following the
discussion group, so they could rattle off some figures like tons of oxygen
production per year per ton of biomass (e.g. "It takes 10 tons of
cyanobacteria to produce the oxygen that 2 tons of trees can produce in the
same amount of time," or whatever the figures are).

Perhaps you're projecting that the vertibrate occupants' need for oxygen in
this settlement will grow slowly enough (i.e. the population will start
small enough) that seeds or seedlings could be transported instead of trees,
and that the numbers of the colony's botannical and zoonotic occupants would
grow at about the same pace.