your map is corrupted. your assets are not loading properly and the foliage meshes are not working. usually this is an issue with the map meta file, unfortunately theres not many solutions and its quite difficult to pinpoint the exact moment of time something went wrong. I can only list the following suggestions

1) if you have any map backups, delete your map files in unturned and paste the backups, then go from there
2) check your map files and see if your system has stored any previous versions of them, and try some (if present)
3) go to your workshop upload for your map, and revert to a previous version
4) throw an unlocker in your file (this only fixes minor corruption on rare occasions)
5) reverify game files (copy your current map and repaste after)

basically, your objects.dat / map.meta /visibility.dat and other important files, are not properly configured to the map anymore/all in sync, this is why its critical to constantly save and backup when editing