When Mrs. Mallard retreats to her room the author describes the scene outside her window 'the tops of trees that were all aquiver with the new spring life' - what does this symbolize?

The description of the trees being "aquiver with the new spring life" symbolizes renewal, rejuvenation, and hope. It reflects Mrs. Mallard's own reawakening to the possibilities of a new life after the initial shock and sadness she felt over her husband's death.