We recognize corporations as legal entities with rights because it makes a great deal of the legal wrangling around, eg, assigning blame for criminal activity, or assigning permissions to operate, more convenient. Assigning rights to trees means not having to draw the entire causal chain to the harms done to people by environmental degradation, which can take years to manifest and is often irreversible. It’s the same legal fiction for the same reason.
This is unnecessary and over-shooting. States and localities are perfectly able to create legislation that specifically protects trees and other living beings and/or the environment in specific ways as necessary to prevent harm to people. You don't need to draw the whole causal chain to sue someone cutting down a tree needlessly all the way to some specific human harm - you just check that their actions contradict the law.
Actually recognizing a tree's right to life would mean extending constitutional limitations on any such legislation, and putting some kind of equality between human needs and a tree's needs, which is absurd: not just impractical, but not even morally tenable.
I think this is the opposite of missing the forest for the trees.
It's not a legal fiction that ~"corporations are people." Corporations are literally individual owners, managers, employees, etc. with various personal rights and responsibilities. There is no forest but for the trees that compose it.