Turn and emphasize.
1. Turning: Dashes can be used in poetry to express turning points in literary meaning, "Then I died, and even my feathers rotted in the earth." The dash here shows the poet's persistence and deepness in the land. His love must be integrated with the land even after death.
2. Emphasis: Dashes can also be used to emphasize a word or sentence, or to supplement certain information, "Why do I often have tears in my eyes? Because I love this land deeply." The dash here plays the role of emphasizing the poet's deep love for the land and highlights the theme of the poem.