I came across a guide to help increase in-game performance and noticed something interesting. At the very end of the guide, the author suggests to remove a file called "plants2_clutter.pbo" located in DayZ\Addons\, launching the game, and moving the file back into its original location. Apparently this completely removes all grass and bushes once you're in the game.

The author also suggests to set all config files to "Read only" to prevent the executable to overwrite them.

I have not tried this myself, so I cannot confirm if it works.

Here's a link to this guide http://steamcommunity.com/sharedfiles/filedetails/?id=517735014