Birch trees are commonly seen in dreams in large numbers such as in a heavy, thick forest. Experiencing a dream where you are running through a forest symbolizes feeling of lost or vulnerability. Though this may seem like a negative symbol, generally a forest symbolizes a place you can find yourself and help heading in the right direction.
A single birch tree represents life, so consider what the environment and the characteristics of the tree could be saying about your waking life. For instance, a tree with dropping leaves could symbolize running out of time while a flourishing tree with birds chirping inside symbolizes a thriving, exciting, and lively life.