Its a simple meme really. Green Diversity equals
Greens find it comparatively easy to curb Humanity's propensity to consume all the world's resources for itself by reminding themselves that, scientifically, the Earth only remains inhabitable because of the interactions of all of its living beings.
So, for example, the oxygen us humans need to stay alive is the waste, the poop, of zillions of invisibly small creatures in the ocean that suck up excessive atmospheric CO2 and poop out oxygen.
Destroy the living conditions these creatures need to survive - as humanity's global warming is doing right now - and humanity will inevitably choke itself to death by its own inability to restrain its appetites.
The second reason that we Greens accept that a diversity of lifeforms is essential for the Earth to remain liveable is that the Universe (and hence the Earth) is an inherently dangerously dynamically chaotic place.
Only a diversity of lifeforms can assure that at least some tiny spark of live survives during each
global disaster, to crawl forth from the wreckage and re-populate the Earth.
This grim situation has happened many times during the 4 billion years of life on earth.
Let us consider a global disaster that almost happened to humanity in comparatively recent memory.
As is well known, the Nazis were unremittingly hostile to any hint of diversity : longing to cut down life until they had a world where all humans looked exactly alike.
An entire world of blue-eyed blondes of pure Aryan stock, symetrically perfect of face, perfectly fit mentally, morally, physically.
The handful of individuals in the then world over 2 billion people who could meet those exacting standards, those perfectly perfect individuals ,would soon have the entire world to themselves.
Because the Nazis also sought to replace all of Nature's little imperfections and vast variety by a few "perfect" products of human synthetic chemistry.
But, luckily in the end, Nazi Germany, the smartest scientific nation on Earth, couldn't in fact built the war-ending atomic bomb.
For they had killed off or scared off all the wide diversity of humanity (& their talents) within the German sphere that were needed to complete this new project.
Instead those fleeing refugees, that unacceptable diversity of humanity, that Big Tent of all possible Talents, instead helped the Allies to win the war..