Determining risk thresholds are an integral part of risk management, yet significantly absent from discussion within the arboricultural profession.  Thresholds define a decision point in which a tree owner or manager would implement heightened mitigation actions to address an unacceptable risk that has been identified.  Conversely, thresholds also define levels at which no additional mitigations would be sought because the allocation of resources would exceed any significant diminution of risk.  This critical concept is both poorly understood, rarely discussed and inadequately researched within the arboriculture and urban forestry profession.  Unfortunately, this environment encourages simplistic and often incorrect assumptions of tree risk in litigation by both attorneys, consulting arborists and arborists.

Using examples from a number of litigation cases and weaknesses in current arboricultural literature, Mark will initiate the session with a discussion on the relevance of the topic to all within the field and detail how this poor understanding of risk undermines our ability to develop reasonable programs for managing tree-related risk and inadvertently skewing discussion in litigation.  The second portion of the discussion will detail the tools for identifying risk thresholds for government agencies and arborists.   From this understanding, municipalities and park systems will be directed on developing proactive, reasonable and defensible tree risk management policies.  For arborists, this understanding will inform discussions with their residential clients on balancing mitigation with tree benefits.