In Greek mythology, Dryads represent forest nymphs who are also goddesses or demi-goddesses.
Dryads live in caves, trees, and groves. Their lives are linked to where they live. For example, if a tree dies (whether it was cut down, struck by lightning, old age, etc.), its dryad dies with it. An example is the myth of King Erysichthon, who had a sacred oak tree cut down. But with the oak died the dryad, belonging to the retinue of the goddess Demeter. Demeter in turn summoned the god of hunger to kill the king.
There were also the so-called Hamadryads, who were tied to a certain kind of tree. For example, Melia was tied to an ash tree.