This is not true at all. Protecting the environment isn’t just about actions like planting trees and buying up the occasional extra property parcel to dedicate as a land reserve. It requires government scale regulation to impose negative consequences on people and companies producing negative externalities.
You can argue that the government hasn’t done enough in this regard, but it’s demonstrably not true to claim that 3rd parties have done more than the government to regulate industry and build national park level land reserves.
This is the problem with most pro-anarchistic stances: They take too much of the current system’s benefits for granted while also assuming that less regulation would somehow produce a more regulated outcome.
I don’t understand the desire to put impossible theories of anarchy on a pedestal instead of simply making incremental improvements to the current systems.