Maintaining Environmental Homeostasis

In the early days at least, atmospheric composition will be controlled with mechanical methods rather than biofeedback. We'll basically be controlling the carbon and nitrogen cycles using storage and pyrolysis to maintain levels. This is known to work in a closed environment, tried and tested.

After that, a Biosphere II-type complex environment could be gradually introduced as we acquire the space and knowledge. Problems such as oxygen shortages and gas buildups won't be a worry given the sledgehammer techniques that we can resort to if necessary. Biosphere II will probably give us a wealth of information on this, but I suspect that the chaotic nature of the processes involved will make trial and error an inevitability.

Most of our flora and fauna will be rigidly controlled and intensively farmed. Free-range biota come under the recreational category and are going to need a lot more room than the initial phases contain.