It looks like it's called Forestation by timeasmymeasure.

I just finished Alera this morning, like the last book, and boy was that a ride. I loved how things circled back to the first book. Amazing world building and I loved that the carnim weren't just wolf humans, the marat weren't just human barbarians, an dwish we could've gotten more of the Icemen. I also loved how even the villains, well, except Kallus, had hints of humanity to them. Or at least were fleshed out enough we could feel a measure of sympathy for them.

If you enjoy good world building, let me suggest the Craft Sequence by Max Gladstone. It is amazing.