How do forests evolve in respect to concentration of coniferous trees versus deciduous trees?

I remember when I was much younger in science cl, we learned that in some climates, forest often start as one type of tree (coniferous, I thought) and eventually evolved into deciduous trees, with the coniferous trees growing faster in the event of forest fires or other disasters, as the cycle repeated itself. On a scenic train ride into logging country here in West Virginia, the guide mentioned that in that part of the state, the tall fir trees (which are coniferous) eventually take over the deciduous trees and if left alone for a century, the forest there would be almost exclusively old growth fir and coniferous trees. I have searched wikipedia and google for the answer but can't find it.