Actually, new thought.
The talk about mountaintop removal projects, and a lingering trace of the discussion about the elven "forest spirit" made me think for a second about the Ancient Greek deities, and how they would battle one another, with their favored cities as pawns or proxies in their wars.
As part of the theme that messing with magic stirs up potential backlashes against you if you do not treat it with proper care and respect, then what about something like a wrath of a forest spirit being a directed, purposeful rage against you, rather than a general "you made too much wild magic appear" type of punishment upon players. If you give the forest spirit power by causing their type of magic to flourish, then abuse that magic to your own liking, it becomes wrathful. If you sap the spirit's strength in the region, then you can do whatever you damn well please, but you don't get any magic goodies from that spirit, anyway.
One of the
discussions back in the "Making HFS More Deadly" thread involved talking about how elves don't so much worship nature as they worshipped the forest spirit - if you created your own natural landscape, but it wasn't part of their forest spirit's domain, then it's not "nature" to them, and is an alien aberration in their eyes. In fact, it might be best to remember the old stories of the Fae rather than Tolkien's elves. (We could always do with being more able to venture out of Tolkien's shadow a little more often...) Their purpose is to nurish the forest spirit, not to protect the trees per se, but to protect the power source of their spirit.
I was also thinking about the entire "drowning out metaphysical elfishness with metaphysical dwarfiness" bit that VoidPointer had said... We have "Mountain" as a sphere, and often as a deity. What if mountaintop removal projects to strip-mine all the valuables would piss off The Stone, the protector, and progenitor of the dwarves? To mine, to explore, to build your kingdom within the embrace of The Stone is to live well, but to desecrate The Stone by exposing her innards to the hateful Sun is blasphemy!