Symbolism of Trees in a Garden

In the following excerpt, the author describes a lush garden where different plants grow together:

"The vibrant colors of the flowers danced in the sunlight, while the towering trees stood as silent guardians, watching over the delicate blooms below. Bees buzzed happily, flitting from petal to petal, a joyful reminder of the life that thrived in this sanctuary of nature."

In this passage, what do the trees symbolize?