The Tall Grasslands on the eastern margin of the plains receive sufficient precipitation to support trees.

Before European settlement, periodic fires were initiated by lightning strikes or set by Native peoples for hunting.

Most trees were killed by the fires, while the herbaceous grasses and forbs can re-sprout from their deep roots or re-grow from seeds.

Human suppression of fires in recent decades has contributed to the decline of prairies and other ecosystems that were historically maintained by fires.