Generally, special seeding is required on Forest Service Property. The state has different ecosystems. Seed availability and cost then determine the final mix. Entire text books have been written to answer this question. One short answer is economics.
Good ecology is critical to good economics.
On the Interstate system the mowings are timed to promote crimson clover in the spring and coreopsis in the early summer. The transition zone is mowed in the fall to keep out woody vegetation and to distribute the seed from the seasons blooms. Outside of this zone, up to 30-40 feet is mowed in the fall to promote herbaceous perennials and to distribute the seed from the seasons blooms. Annual mowing is required to maintain sun-loving wildflowers in Arkansas. Native herbaceous perennials cannot compete with woody vegetation.