Check the stacks of lumber at the Rahaba Lumber Mill for the clue to Dufrane's treasure.
The tree mentioned in Dufrane's code has been chopped down. Check the nearby lumber camp to see if they still have the unprocessed timber.
This stack of lumber is freshly cut.
This stack of lumber is the same type of wood as the trees around the Forest Hut...
Inside you find half of Dufrane's decoder.