Stew, yes it is a dramatic change in vegetation! The stereoscpe picture would have been taken in winter [dry season, April to Oct] because the mountain aloes are in bloom, and the colour picture is in summer [wet season, Oct to April]
What you see is a welcome increase in lovely paper bark Acacia trees in the Game Reserve below Spion Kop - plus a more general aggressive overgrowth of thorn bushes, mainly outside the Game Reserve. Thorn bushes are now so dense on the slopes of Mount Alice and Swart Kop that you can no longer walk in many places. It's impossible to climb the NE slope of Spion Kop where the Carolina Cdo climbed up. Nobody seems to have an easy solution.
The past is not dead. In fact, it's not even past.