Trees in urban environments face many challenges. Here's a list that show some.
Conflict with Power Lines
This is a common site in most urban areas. Unfortunately for trees maintaining uninterrupted and safe electricity takes precendence over ANSI 300 pruning standards.
Stubbing of Branches
There are a lot of ways that untrained pruners damage trees. This is far too regular occurrence.
Raising the Grade
Perhaps less obvious to some is the fact that adding soil over the trunk and root area kills the tree. Though it may take a while to die.
Compaction during Construction
Even small machines cause future problems when working too close.
Lawn vs Young Tree
Tree loses
Concrete vs Young Tree
Tree loses
Misguided Pruning Saw vs Young Tree
Tree loses