Why does heidi have to leve the alm?

Heidi has to leave the Alm because her grandfather, Alm-Uncle, decides she should go to Frankfurt to live with her new friend Clara, who is in need of companionship and support due to her disability. Although Heidi is deeply attached to her home in the mountains and her grandfather, this move is seen as an opportunity for her to help Clara and experience life beyond the Alm. The transition is difficult for Heidi, as she longs for the simple joys of her alpine life.