Excellent work so far. I just purchased to support you. Here are some things I would like to see you improve in the future for your work.
1. Have the "stone tile" tile have angular brakes on one tile and another. This will help map designers create more angles for paths and walkways.
2. Try and make more types of tree's for Boreal and Arid climates.
3. More plants and bushes for water and ground.
You are already making a great start. Keep it up and hope to see more from you.