Symbolism of the Oak Tree

In a short story, the author describes a character named Sarah who often gazes out of her window at a large, old oak tree in her backyard. The tree stands tall and strong, with its branches spread wide, providing shade and shelter to various creatures. In a key moment of the story, Sarah reflects on how the tree has witnessed many seasons of her life, from childhood games played in its shadow to her struggles as a young adult. This moment of reflection symbolizes a connection to her past and her growth over time.

What does the oak tree symbolize in this passage?