Generic Forest Health Surveys Guidebook

Table of Contents

Hazard and Risk Rating

Hazard and risk rating can be used to rank future monitoring, silvicultural treatments, or harvesting. The rating allows the identification of problem areas and to better focus limited time and resources.

A hazard assessment of forest health factors should be conducted in compliance with an FDP, or on a stand for which a prescription is being written. The results of the assessment can be used for predicting the future risk of pest caused damage.

Attributes of Hazard and Risk Rating

With regard to forest health factors, hazard and risk have separate and distinct meanings. Hazard means the degree to which the characteristics of the tree or stand make it vulnerable to damage. It is equivalent to the word "susceptibility." Risk is the probability and expected severity of tree or stand damage. Risk is a function of hazard, and also considers the pest pressure on the stand under consideration.

Attributes commonly used in hazard and risk rating systems:

BEC unit
tree species
species mix
stand structure and density
site factors
tree vigour/stress
tree age
past forest practices
current environmental conditions
predator presence or absence

Pest pressure
proximity to or presence of damage agent
timing of next outbreak cycle (periodicity)
point in outbreak cycle
area or quantity of damage

Available Hazard and Risk Rating Systems

An evaluation or assessment of forest health factor occurrence or incidence must be incorporated into FDPs, silviculture prescriptions, and stand management prescriptions. For this purpose, a hazard (or risk) rating system is the most useful application. Hazard rating systems are available for some defoliators and some bark beetles. Only general guidelines can be offered for rating disease hazards. The hazard rating systems presently available are described in the guidebooks for defoliators and bark beetles.

The Forest Health Network Archives Pest Data for British Columbia website is available from the Canadian Forest Service at the following site: This web site contains the Forest Health Network aerial detection survey coverage for British Columbia. These pest coverages are stored as an ArcInfo coverage format and are converted to an ArcInfo export file (.e00) format for file transfer protocol (FTP) purposes. The coverages can be selected in four different ways: by mapsheet, by region, by region as historical summaries from 1911 to 1985, or for the whole of the province.


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