If your fortress butchers too many animals, or cuts down too many trees, or gathers too many plants (designation plant gathering, farming is fine), then a horde of wild creatures will arrive to besiege your fortress and put an end to your atrocities against nature.
Hell this could even give elves context.
You find an ancient book amongst the belongings of a dead elf
~Ancient book - written in human~
At first our people were no different than humans, we took from the land to build temples honoring the gods and great walls for protection. Great tales were told of adventures to faraway lands, where sun berries grew, and feathers coated the earth, and all manner of food and tree were plentiful. The kings sent many an expedition to colonize these places, and here our people prospered, it seemed that all around, there was no end to the bounty of the land.
Then they came.
A tide of fur consumed our towns, our temples were destroyed, our walls could not keep out the winged assailants, our dogs turned on us, and the sewers ran red with blood. Though they did not speak any human tongue, their demands were clear, submit to the will of nature, or die.
For thousands of years, my people lived in fear, under the rule of the animal kings. No longer would we know the protections of four walls and a roof, or the warmth of a fireplace, for tree cutting was forbidden. No longer could we document our history, for writing with the ink of an octopus and the feather of a bird was punishable by death. Though many secretly held strong the beliefs of the old gods, we could no longer construct temples in their honor, instead, we were forced to create crude and simple temples, to honor the titans which ruled over us.
In the trees we now lived and depended, we grew short, thin, and agile to survive, our ears became more perceptive, and grew to points. Our language changed drastically, many of the hard consonants used by humans faded from use, as our people chose to speak softly and quietly to avoid being overheard by our rulers.
- Here the writing changes to elf -
As it no longer seemed apparent that elves and humans could be related, trade was allowed, but only under the watchful eye of our masters, do not be fooled, those "pack animals" may carry our goods, but their eyes watch our merchants and report to our masters, even in faraway lands, we can never be free.
How do I know all this you may ask, among the oldest of the human cities, I was sought out by a man who would not speak his name, and he gave me this book, I have hidden it among my possessions and write in it when the mules are grazing. He would only tell me that this was a documented history of my people, passed down and copied many times through many generations, and that all elves must read it and rise again to truly be free. Though this book has taught me much, our rulers have many spies among the elves, the druids are but puppets, I cannot trust it to anyone.
I am Ririli EarthOrders, elf merchant. Our caravan has visited many towns and mountain halls, and in each we have pleaded that the inhabitants to cease cutting down the forests which surround them, only to be scoffed at and ignored, little do they know, and I cannot tell them, for when I speak too loosely I can feel the breath of a Donkey at my back, ever-present, waiting for me to make one mistake.
It is in the mountainhomes where I see what you might call 'freedom', the dwarves submit to no gods, purge the members of their society which believe themselves as rulers, reap the lands with no concern for anything but the booze in their barrels and the steel in their forges. They seize our goods, and I sense the mules at my back, I can only utter the words "take what you want, there's nothing I can do", the feeling of submission is never far from the elven heart.
I cannot live like this any longer.
Upon reaching the nearest forest retreat, I will tell the elves of the 'atrocities' committed by the dwarves against nature, against our rulers. I myself will lead a war party against the dwarven halls, which I have seen first hand, the walls there are insurmountable, their defenses impenetrable, even the armies of the goblins would fail against the mechanations of the dwarves. My brethren do not know this, but I know one thing, I would rather die under bolt and hammer, than horn and hoof.