Forest M&M Definitions

Forest Measurement and Modelling.

General forestry online definitions

One-Look Dictionaries {}

IUFRO Unit 6.03.02 Trends in forest terminology {}

Natural Resource Inventory Glossary {}

North Caroline Cooperative Extension Service: Woodland Owner Notes {}

Terminology Collection Online Dictionaries: Forestry {}

Glossary of Forest Terms, Natural Resources and Environment. {}

IUFRO SylvaVoc {}



Refers to the closeness of a measurement or estimate to the true value. Accuracy may be used in either a qualitative way or as a quantitative summary of total [error].

  • Qualitative: An accurate measurement is one where the total error is small.
  • Quantitative: A2 = B2 + P2
    where B denotes a measure of [bias] and P denotes a measure of [precision].


A systematic distortion in a measurement or estimate.

Dominant tree

A tree with a crown that receives full light from above and partly from the side; usually larger than the average trees in the stand. Dominant tree crowns usually extend above the general level of the canopy and are well developed but possibly somewhat crowded on the sides.



The difference between an estimate or measured value and the true value.


The value of a parameter or variate obtained indirectly.

The average height of a stand of trees may be estimated by measuring a sample of trees and calculating the average from this sample.


There is no universally accepted definition of forest. This is because the minimum size of an area and the minimum density of trees on that area is subjectively selected by the different forest management organisations to meet their own needs.

The definition used by the National Forest Inventory {} quantifies the minimum area, the smallest potential tree height and the amount of crown cover:
an area, incorporating all living and non-living components, that is dominated by trees having usually a single stem and a mature or potentially mature stand height exceeding 2 metres and with existing or potential crown cover of overstorey strata about equal to or greater than 20 per cent. This definition includes Australia's diverse native forests and plantations, regardless of age. It is also sufficiently broad to encompass areas of trees that are sometimes described as woodlands.

Forest mensuration

An extension of [mensuration] to include measuring the growth and change in forests.

The art and science of providing quantitative information about trees, stands and forests for forest research, planning and management.




The determination of size in relation to some observed standard, e.g. metre, kilogram, second, ampere, degree Kelvin, candela, mole or some unit derived from these seven basic units.

Essentially, when you are measuring you are counting the number of standard pieces it takes to be the same size or quantity as the object of interest.


The art and science of locating, measuring and calculating the length of lines, areas of planes, and volumes of solids.

Natural Basal Area

The basal area, determined by site capacity, towards which even-aged stands will tend to converge.


A characteristic which describes the whole or part of a [population] in some way.

The average height of trees in a forest is a parameter that partially describes the population. He area occupied by the forest is also a parameter of that forest.


An aggregate of items, each with a common characteristic or set of characteristics that are of interest. In a statistical sense, a population is an assembly of all possible individuals (units, measurements, observations, etc.) that meet a specified and well-defined objective.

All the trees in a farm woodlot could be one population. Alternatively, if there were two species in the woodlot, the population could be defined as all the trees of one species only - the other species could be treated as a different population. The clear definition of the population is important to avoid inappropriate extrapolation of results from measurements.


  1. The fineness of a single measurement. This relates to the resolving power of the measurement device. For example, a scanning electron microscope can be used to take more precise or fine measurements than a hand magnifying glass.
  2. The degree of agreement in a series of measurement. For example, the list of measurements [3, 2, 3, 3] is more precise than a list [4, 1, 3, 1].
  3. Clustering of sample values about their own average.
  4. The reproducibility of an estimate in repeated sampling.

Definitions 2, 3 and 4 indicate that precision is freedom from variation.



A representative sub-set or portion of all units that are part of a [population].


Thickening of vegetation is a change in carbon per unit area arising from human induced changes in grazing or fire regimes. Vegetation thickening usually involves an increase in the biomass of woody plants, (measured as an increase in basal area and height) and often a simultaneous increase in soil carbon and dead plant material. It typically results from an increase in grazing intensity and constancy, which per unit area lead, along with other management actions, to a decrease in the frequency and intensity of fires. The species of woody plants involved may be native or exotic.



A characteristic which may vary from one individual in a [population] to another. It relates to some feature or property of an individual in the population.

Variables may be classified as:

  • Continuous variables
  • Discrete variables

The height, diameter, volume or leaf biomass of a tree is a tree variable.


An observed value of a specified variable for an individual in a population.

[definiti.htm] Revision: 6/1999