Answer:
Trees ; sod
Step-by-step explanation:
The prairie region is covered by large amount of Grass with little to no trees. In order to built shelter that protect them from cold weather, many people who live in this area build cabin by using the combination of clay and grass. This combination is most commonly known as sod.
Compared to using woods, sod houses provide less protection from the weather and weaker structures. But, it's a perfectly good alternative for the people in prairie considering that they do not have other better resources