Prevent certain roles to edit or add any pages under a certain path

[PascalKonings]

For my site I would like to add a few editors with specific roles, to manage their bits of content and add new pages, but only below a certain part of the tree. Since I have a generic set of templates, I can't limit access or content management by template, because all templates should remain selectable when creating content. 

What is the preferred way (hooks or other default settings) of restricting access to a certain part of the tree, without doing so based on template family rules?