Complex sentence: The non-farming part of the park is maintained as open after ice-age landscapes, done by cutting down excesive tree growth that would otherwise cause of natural, and dense, forestation, obstructing view and accesability.
Split into simpler sentences: The non-farming part of the park is maintained as an open, after ice-age landscape. This is done by cutting down excesive tree growth that would otherwise cause natural, and dense, forestation, obstructing views and accesability.