BMP - Tree Risk Assessment - 1

Preface
The International Society of Arboriculture (ISA) has developed a series of
publications known as Best Management Practices (BMPs) to aid in the interpretation of professional standards and to guide work practices based on
current science and technology. These publications are intended as guides
for practicing arborists, urban foresters, tree workers, and their supervisors.
This BMP was developed to be consistent with the International Standards
Organization standards ISO 31000:2009 Risk Management-Principles and
Guidelines, IEC/ISO 31010:2009 Risk Management-Risk Assessment Techniques, and ISO Guide 73:2009 Risk Management-Vocabulary; American
National Standard for Tree Care Operations-Tree, Shrub, and Other Woody
Plant Management-Standard Practices (Tree Risk Assessment a. Tree Structure
Assessment) (ANSI A300, Part 9); and other national standards.
One way in which the ANSI Standard differs from some of the other
standards is that it addresses only tree risk assessment and not the overarching goals and issues of tree risk management. In addition, the ANSI Standard
is aimed at guiding the practices of arborists, not tree owners or managers.
This BMP is similarly aimed at arborists who perform tree risk assessment
and does not incorporate comprehensive guidance for tree risk management
or for owner/manager practices or responsibilities.
Tree risk management is the application of policies, procedures, and
practices used to identify, evaluate, mitigate, monitor, and communicate tree
risk (Figure P1). Various people share responsibilities for tree risk management-including the tree owner or manager, the tree risk assessor, and the
arborist providing service work (Table P1).
This document is intended to serve as a guide for arborists to assess tree
risk as accurately and consistently as possible, to evaluate that risk, and to
recommend measures to achieve an acceptable level of risk. In doing so,
tree risk assessors should recognize the value of preserving trees and the
importance of avoiding unnecessary treatments. It is not the intent of this
document to provide direction for developing risk management policy or for
providing legal guidance.
It is impossible to maintain trees free of risk; some level of risk must
be accepted to experience the benefits that trees provide. The National Tree
Safety Group (NTSG), which is a partnership of organizations in the United
Kingdom, has drafted a guidance document that identifies five key principles
for tree risk management. This document provides a foundation for balancing
tree risk and the benefits that trees provide:
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BMP - Tree Risk Assessment

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