[guard-of-terra]

You should not overstate how Earth ecosystem is "delicately balanced". Large deserts where vegetation used to be. Ice ages (and inter-ice periods) really messed up northern fauna: all megafauna went extinct, wooly rhinos, mammoths, sabertooth tigers, etc. Without them the ecosystem is incomplete and disbalanced.

[Retra]

Compared to what? What parameters are you 'balancing?'

[guard-of-terra]

In my opinion, balanced ecosystem is one that a) diverse, b) produces as much as life as possible for a given landscape.

Why diverse? Diverse ecosystems are more resilient against shocks, changes and diseases.