Generic Forest Health Surveys Guidebook

Table of Contents


Current attack (also called green attack): a tree attacked by bark beetles that still contains beetle life stages. The tree may still appear healthy, but show signs of beetle attack.

Forest health factor: biotic and abiotic influences on the forest that are usually naturally occurring components of forest ecosystems. Biotic influences include fungi, insects, plants, other animals, bacteria, and nematodes. Abiotic influences include frost, snow, fire, wind, sun, drought, pollution, nutrient problems, and human-caused injury.

Geographic Information System (GIS): a computer system designed to allow users to collect, manage, and analyze large volumes of spatially referenced information and associated attribute data. The major components of a GIS are the user interface, database management, data entry, product generation, and spatial data manipulation and analysis. These functions may be centralized, or distributed across a network.

Global Positioning System (GPS): a navigational tool that allows the user to determine their location on the surface of the earth (usually within metres), using a hand-held or aircraft-mounted instrument linked to radio signals from several satellites.

Hazard: the degree to which the characteristics of the sampling entity (usually a tree or a stand) make it vulnerable to damage. It is equivalent to susceptibility.

Hawksworth Six-class Rating System: a standardized method of assessing the severity of dwarf mistletoe infestations on a tree. The method is fully described in the Dwarf Mistletoe Management Guidebook, Section 5.3.

Incidence: the proportion (0–1) or percentage (0–100%) of damage agent–affected sampling entities (normally a tree) within a sampling unit (normally a plot or a stand). To avoid confusion when using incidence, always indicate the sampling entity and sampling unit in order to ensure clarity. Where the proportion of damaging agent–affected stands or polygons (sampling entity) is of interest in a higher-level sampling unit, use occurrence.

Intensity: a general characterization of the total amount of a damage within a specific population and a function (not necessarily arithmetic) of incidence and severity.

Inventory Type Group (ITG): the designation of species composition by one of 42 type groups, each one being a unique combination of pure or mixed tree species.

Multi-storey: A stand is considered multi-storey if the layers 1 or 2 have a crown closure >6% and one of these layers is in combination with layer 3 and/or 4. In order to survey using the multi-storey method, an opening must have at least a minimum of three layers present or one of the following combinations: layers 1 and 4, layers 2 and 4, or layers 1 and 3.

Occurrence: the proportion of damage agent–affected stands or polygons within a higher-level sampling unit (e.g., inventory or growth type groups, or BEC zone subzones or variants).

Pest: any forest health factor designated as detrimental to effective resource management.

Pixel: a type of fixed plot used to estimate prevalence as the percentage area infected; often only the presence or absence of the damaging agent is recorded for each pixel.

Population: a collection of sampling entities about which we wish to make an inference.

Prevalence: the proportion of sampling entities (in a given population of interest) affected by a particular damaging agent.

Probe (beetle): a systematic strip transect survey through a stand to obtain detailed information on infestation levels, history, and stand data needed to make management decisions.

Risk: the probability and expected severity of sampling entity damage. It is a function of numerous components, including sampling entity, hazard, sampling unit conditions, proximity to damaging agents, and the incidence of those agents.

Sampling entity: an object on which a measurement is taken (normally a tree or a stand).

Sampling unit: a non-overlapping collection of sampling entities from a population.

Severity: the quantity of damage, or the quantity of a damaging agent, affecting sample entities within a sampling unit. It is a damage-rating measurement, (an average) that considers only affected entities and is damage type or agent specific. Severity cannot be applied at the stand level. The terms intensity, yield/growth effects, or impacts should be applied at the stand or higher levels.

Strip: a sampling unit laid out by measuring an equal distance on either side of a transect; a special type of fixed plot; other names include strip transect, probe line, and strip plot.

Susceptibility: term equivalent to hazard.

Walkthrough: an initial reconnaissance of an area; for bark beetles a non-systematic, low-intensity type of ground survey assessing damage. Used to make initial assessment of situations and confirm aerial survey information.


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