Like the mythical bird a phoenix tree rises up after death, but in this case not from fire but from falling over or snapping off near to the ground. Both of these occurrences would normally kill a tree, but sometimes the tree lives on.
In the case of trees which fall over, usually from a strong wind, if there are sufficient live roots still attached the tree can continue to live. What were once side branches become new trees growing along the fallen trunk.
Over time roots are created beneath each branch where the trunk is in contact with the soil and eventually the original trunk can decay and disappear leaving a row of trees arising from the one fallen tree.
Very large trees that snap off at their base can sometimes have many new limbs growing around the edge of the broken trunk which can develop into a circle of new trees.