I have worked on several prairies in the last several years. I have found that in most of the areas, there is enough native vegetation that comes back from the existing seed bank once the cedars are removed that its not necessary to plant anything. The only problem I have had is in the places that we piled the cedars to burn them, it got so hot that it killed a lot of the native seed bank. The big key is to keep the areas burned at a regular enough interval to inhibit the woody plants from returning.