Stem-girdling roots and dysfunctional root systems are 2 very big problems with trees, especially in urban landscapes. The good news is that they are totally preventable. Trees just simply need to be planted correctly! Learn more about stem-girdling roots (PDF)and scroll down and view the pictures.
Obvious SGR's encircling around this maple
A dysfunctional root system; roots are growing every which way
Mid-July and the leaves are already turning on this Autum Blaze Maple -a clear indication the tree is stressed
This is why: the tree above has a dysfunctional root system containing SGR's
Early summer and this Linden never leafed out?
This tree was planted in a landscape bed and the blocks have caused the roots to become dysfunctional; also, it was planted too deep
This is how the roots should be growing on a tree- out and away from the trunk
Here we have the results of trees with SGR's in a wind storm