What is the poem "Birches" by Robert Frost about?

The poem "Birches" by Robert Frost is about birch trees in a forest and what causes the limbs to arch and bend. The author initially imagines that the arches are caused by a young boy swinging on the branches.

As the poem progresses, the author concedes that the bending branches are likely caused by ice storms, with frozen water causing the limbs to be weighted for so long that "they are dragged to the withered bracken by the load." Frost reminisces about boyhood and prefers that the limb of the birch had been bowed by the play and exploration of youth.