Fly-tipping is not just in the car parks. Cowboy builders are one thing. Cowboy conservationists are worse because they're using public money to do it, and they try to justify their laziness with spurious claims it's good for the environment.
Essentially it's the same thing. They do what they claim is a job of work - in this case cutting down trees. Most inconveniently there's stuff left behind and unwanted when they've finished. They don't want to dispose of this so they shove it somewhere out of the way and leave it. Just like the cowboy builders. If the trees could express a view would they choose to have the corpses and severed limbs of other trees pushed against them and left there? Does SRWT claim this is pretty? I wouldn't be surprised if they did.