I haven't had much experience with destroyed scenery... but, from the top of my head - when cloth is ripped you might have threads hanging loose, or just a couple still attached in the middle of a large hole.
Mechana suggested jagged, sharp lines - that's what I was thinking as well. If you are drawing vegetation, perhaps even what vegetation has survived is withered, has jagged, ripped edges on the leaves, half-broken branches hanging at funny angles... curled leaves....
Probably nothing that you didn't already know, but I hope it helps, anyway.