Until we actualy get into a space station, the botanists and the forestry engineers will be needed to ensure that the growth of the city, if there is one to be in the future too, sincei it is not quite sure yet, don't over step the necessity of the plants presence.
Some limits recommendations should be done by these workers.
For the space part; we should take in consideration the hydroponic systems to grow our large variety of plants. May be for food or medecine.
Until a station get large enough to sustain actual trees, a botanist would be more than usefull to suggest wish type of plants would be more needed than others, and why. This implement a listing of such plants (ex: tomato ... how to grow the plant itself ... what type of plants could be potted in the same area to help each other to grow properly ... is there some type of insects to consider a necessity for it ... etc)
And, it is no secret that plants bring us oxygen.
Another thing. Our waste. Would we use these for plants? Compost could be process in a closed system and brang in a way to the plants, maybe by some pipes.