By the time large-scale structures can be built on Mars, the maintainance will probably be largely automated as well, and the mining of materials and manufacture of parts will have to be at least partly automated. The initial construction will require automation anyway, since any construction crew on-site will need life-support while they're working, which will require at least a moderate-sized greenhouse. The fewer people involved at that point, the easier the logistics. But on Mars, the starter settlement need not be a totally closed ecosystem, as raw materials (CO2, small amounts of H2O) are closer than shipping them from Earth. As more advanced colony structures are built, closure efficiency will increase, if only to save energy.

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"If this were play'd upon a stage now, I could condemn it as an improbable fiction."
Shakespeare, Twelfth Night
Illuminati's Razor-The most complicatedly evil answer is usually the most correct answer. - Fazor
"Every book is a children's book if the kid can read." - Mitch Hedberg
"Distance doesn’t matter much in space, where if you just start a thing off with the right kind of shove, sooner or later it will get where you want it to go." -Frederik Pohl, Mining the Oort