I like nature conservation - the idea of creating protected areas where nature lives on its own and wilderness is "created" like that. Is is possible to raise the natural value of land only by leaving it on its own - I mean in the way that humans do not touch the land in any way (buildings, roads etc.)?

I know about some "private" protected areas in Europe, where NGOs thought this piece of land should be protected but the authorities failed to do so, so they bought the land and took care of it themselves (restricted public access to help conservation, removed invasive species etc.)

I wonder what does it take to correctly protect an area - is it OK to leave the land alone and never touch it again or is it necessary to take care of it somehow. I mean things like invasive species (I can imagine the normal "unprotected" nature is full of them) like various types of grass, invasive animals etc. I can imagine this may be largely location dependent (some parts of the world are more influenced by humans than others). My location is the Czech Republic.