A burned forest will come back as a forest, a burned prairie will come back as a prairie. The forest will take longer to come back, of course. Selection pressures don't change that much in the short term, so whatever vegetation was favored in a given location before will probably be favored in the same location after. That, and all of the right seeds are already there. Some pines, like lodgepole pines, can't reproduce unless there has been a fire--high heat is needed to release the seeds from the cones.