Will you please state any example, anywhere in the world, where significant swaths of privately-held, economically-productive land have resulted in long-term preservation of the inherent ecosystems in the absence of intervention from regulatory action?
You know, just anywhere in the world?
Yes.
http://www.nationaltrust.org.uk/I could go on and make a list, but it only takes one counter example to refute your point.
To give a broader perspective,
an eighth of the world's protected nature reserves are privately owned (
http://www.economist.com/node/748602). This is
in spite of government interventions.
People don't need to be coerced into doing good things.