What do the Reds led by Ann believe about the effects of terraforming on possible life on the planet in the novel, Red Mars?

The Reds, led by Ann, are highly concerned about the effects of terraforming on possible life on the planet. While even they admit there is little possibility of life, they still maintain the only way to be sure they are not killing other life forms is to not change the atmosphere drastically enough to kill any existing life.