I get your point, but I'm not sure socialism is the right term.
Socialism, it if has any meaning at all that covers its wide diversity, means the political ideologies that have human well-being and equality, especially economic equality, as their first priority. (We'll leave out of the discussion whether this has any relationship whatsoever with what they do in practice.)
For your deep environmentalists this is no longer their first priority. In fact, they want to regress humans and drive down their numbers. The health of the ecosystem is much more important than human equality or even prosperity and health.
I'm not sure what to call such an ideology, but I don't think it's really socialist. Though many socialists support it to varying degrees.
“Socialism, it if has any meaning at all that covers its wide diversity, means the political ideologies that have human well-being and equality, especially economic equality, as their first priority.”
Basically all recent political ideologies, stretching back to the 18th century, praise welfare and at least some level of equality. ThThis includes much maligned supposedly rigidly hierarchical ones like fascism. Socialism is not special in that regard. They are special in the extent to which they emphasize equality. But that does not define them; what does is their trust in the abolition of private property and the total centralization of economic coordination. If you’re looking for a term to pinpoint radical welfare and equality, you can say “welfarism” and “egalitarianism.”
“For your deep environmentalists this is no longer their first priority. In fact, they want to regress humans and drive down their numbers. The health of the ecosystem is much more important than human equality or even prosperity and health.”
This is so for some, but for the movement as a whole, it’s only one more step on the road towards socialism, which they honestly believe will, eventually, bring welfare and equality. They want to tear down civilization in order to do it again, this time correctly. You’ve heard the saying “you wanna make an omelet you gotta break a few eggs.” Same thing.
“I’m not sure what to call such an ideology, but I don’t think it’s really socialist. Though many socialists support it to varying degrees”
See, I don’t think it is an ideology. Ideology doesn’t really apply to societies of non-humans. Whatever your plan is for what happens after humans leave...whoops, you can’t have a plan, because no one will be there to implement it. For those who truly believe in Earth First, if they have an ideology, it have to be purely negative. A form of nihilism, perhaps, or primitivism, atavism, whatever you want to call it.