How do forest soils differ from prairie soils?

Prairie soils developed many yards thick, whereas forest soils tend to be much thinner.

Prairie grasses grow very deep roots, then when buffalo came along and ate it or trampled it, the plant sheds those roots to match the above-ground growth. The green leaves regrow every year, or several times a year according to this pruning. The shed roots and any trampled or dead leaves become compost which improves and thickens the soil.

Forests do not have such fast soil development, because their only source of new compost is generally from leaves as they fall, or occasional trees when they fall. The accumulation of biomass is much slower. Evergreens do not shed yearly leaves like deciduous trees, so they develop soil slowest. Also, evergreens tend to grow acid soils compared to prairies.