HS2 isn't about speed, indeed it's entirely the wrong name: It is about *long distance non stop* services on their own rails getting out of the way of slower stopping services.
And because of the removal of the fast services from existing lines a lot more regional trains can run!
Regarding trees and wildlife, a rail corridor is way narrower than a motorway one, and HS2 is routed to avoid the worst damage, as opposed to the substantial number of by-passes and trunk road improvements being undertaken at the moment which don't.
Improving train services will increase modal shift from road to rail, for passengers and for freight, and massively reduce NOx and CO emissions too, benefitting us all. The sooner it is completed the better.