The best example for what I am trying to describe would be the worlds of Adventure Time, and The Dark Tower series.
These worlds both developed following a cataclysmic war that destroyed a relatively modern/advanced civilization, after which the by-products of the war (basically radiation, but it's technically not radiation so not bound by those rules) mutated the surviving flora & fauna as the world recovered.
I'm currently working on a world similar to these, with the apocalypse occuring in the late 1980's/early 1990's. In this world, the planet has more or less fully recovered. Although there are sure signs of the apocalypse, ecosystems like forests and other lush environments once again exist.
My question is how long would it take for the world to recover following an apocalyptic event that wiped out 90% of the worlds plant/animal life?
I will define "recovering" as the reappearance of robust and diverse eco-systems regardless of whether or not those ecosystems are even remotely similar to the pre-apocalypse. As far as human habitability goes, just assume that in these recovered/mutated worlds there are edible flora/fauna.
The type of destruction would be caused by war, so the scale of destruction would be consistent with all-out nuclear warfare preceded by years of conventional global conflict.
To address the comment concerning what the remaining 10% of life consists of/ if it is concentrated in one location or not:
I would say that the remaining 10% of life consists of random populations of certain random species scattered all over that just happened to be lucky enough to survive the main cataclysmic event of this apocalypse because of geographic protection, as well as species that are simply resilient enough to survive (No getting rid of those tardigrades)
EDIT: I specified that the "radiation" was not technically radiation because my world isn't constrained by the mutagenic effects of real life radiation, however I'm realizing that doesn't help anybody answer my question.
When it comes to contamination just consider it normal radiation/nuclear waste.