Could life in solar system complicate space settlement?

On Mon, Apr 16, 2012 at 6:31 AM, sraj wrote:
> When plants and animals are grown for food production, their bi-products
> should be sufficient to support the biosphere. Heavy industrial processes
> will be needed only as back up (especially in small space habs). The
> ultimate craftsmanship will be to produce a system which supports itself,
> like the conditions we have on planet earth.

We don't have those conditions on Planet Earth. The difference between
Earth and a miniature ecossystem is only one of dramatically different
scales of time and space. Earth *is not* perfectly balanced, quite on the
contrary - in fact many of the mass extinctions in the past were caused by
the biosphere itself. Indeed, nowadays there is the Medea
Hypothesis,
which states (based on many events recorded in natural history) that life
on Earth in fact crashes now and then.

> It is good to keep in mind that humans are still to figure out what makes
a
> natural forest so productive. It is not just the plants themselves, there
> is huge synergy between all types of plants and animals and lower forms of
> life in the ecosystem.
(...)

I am sorry, but natural forests aren't that productive. In the rainforest
at least you can walk for days without finding edible fruits or game, and
it is very easy to die of starvation if you get lost; that's why the army
gives jungle survival courses to the soldiers.

Indeed, the whole story of agriculture is one of multiplying by artificial
selection and supplementation the originally low productivity found in wild
counterparts of domesticated crops and animals.