You're presenting the wrong alternatives. It's not preserving nature vs. letting others harvest resources they will use in part to make babies. Rather, it's preserving nature vs. harvesting it for myself and using those resources for whatever I want (which does not include babies).

The argument of the OP (and others) which I originally answered, was that nature should be a sort of trust, and should not be exploited by this generation. That morally, we should leave it no worse than we found it for future generations. Hence my argument that I can't trust future generations.

Preservation is great if we can enjoy the preserved nature as parks, etc.(*) But preservation purely for the sake of preservation isn't so great, and that was my point originally.

(*) On the market the value of nature as "resources" is clearly higher, in large part because the incentives and responsibilities are all set up wrong. It follows that we can economically harvest all the resources we want and use the profits to set up parks, preserves, etc. which would be tailored to human enjoyment and so much more pleasant for most people than really wild nature.