I just noticed something peculiar.  Found a really nice piece of terrains with trees, and created a pioneer to bring up there.  But by the time the unit arrived, all that were left were burnt out trees.  Do those kind of environmental changes occur in the game?  Possible culprits: a horde of elementals coming down from their turf, presumably to have a poker game.  A fire elemental added to one of my parties.  A party member who a fire shield spell whose name I forget, capable of administering damage when hit.

 And will those trees ever grow back in the game?  Or should that pioneer unit take up another hobby, such as knitting?