Ecosystem is not just massive scale things. What about the Howard Odum's jar ecosystems? Keep them well sealed and they may go on indefinitely.
Plant creates Carbohydrates from air with light, little mites eat the organic debris and release CO2, the plants reuses it to create more plant, and so on. Ecosystems always strive for abundance.
We'll see how this works out =)
@arteteco Always wanted to create a self-contained ecosystem. Let me know how it goes.