An option would IMO be to \"grow\" forests. Similar things are done everywhere. You \"seed\" it (like seeding a randomiser) and then have a set of pseudo-random functions generate a reasonably unique forest based on the seed and certain manual parameters (like predefined paths, hills, rivers, whatever). The result would then be saved and put in the zone. After creating the function(s) once, it can be used to create almost infinite numbers of forests with minimal effort. This way, nobody would have to individually place plants to create a forest, but the plants would be distinct objects and thus the forests roamable. By periodically using this function(s) on a particular forest, you can have the forest change, adding mystery to it. There could also be \"morphing\" functions, which would create a set of transitions (ideally using the current state as basis, so that player-made modifications would affect the cange), to gradually change the forest so that it is \"alive\", just like a real forest. I think the number of objects wouldn\'t be greater than in a library with distinct books, so it should be feasible, but maybe I\'m wrong.
I\'d like some matrix if it was voluntary!
