Structural failure or severe defects. Splits, decay, root failure, or major storm damage can change the risk profile.
Dead or declining tree. Decline can reduce the value of preservation when the tree creates an unacceptable target risk.
Site conflict. Some trees outgrow their relationship with structures, utilities, hardscape, or future construction.
Project need. Removal may be part of a broader property change, but the scope should still account for access and cleanup.