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Tree and forest measurement
Whether it is a trailer load of firewood, a
truckload of sawlogs or a trade in carbon credits the quality
and quantity of any forest product need to be assessed. Both
buyer and seller must agree on the product criteria and method
of measurement. Being able to measure tree growth also provides
farmers with an understanding of forest growth and productivity,
and provides a basis for planning forest management actions.
This section provides an introduction to the
measurement of trees and forests for timber production. It
includes details on how to establish a measurement plot, how
to measure tree diameter, height and stand basal area and
how to calculate tree and stand volumes. Most of the methods
outlined assume the use of cheap equipment and basic mathematical
skills. Although the techniques have some limitations, and
may not be appropriate where a high degree of accuracy is
required, they are suitable for most farm forestry situations.
While the emphasis is on measuring forests,
standing trees and logs for timber production, the same measures
often form the basis of assessments of forest services such
as carbon sequestration, biodiversity and water use in recharge
areas.
Basic tree measurement tools
The most basic tool of forest measurement is
the diameter tape. By wrapping the tape around the trunk of
the tree the user can read off the diameter. Accurate measurement
of tree height generally requires more sophisticated, and
therefore expensive, equipment. However outlined here are
some simple, inexpensive techniques for estimating tree height.
They are suitable for many purposes. A good quality 20 or
30 metre tape (available from most hardware stores) and a
calculator are all that is required to complete all the measurements
outlined in this section.
Other equipment that is useful for tree
measurement and data analysis include a pocket knife for measuring
bark thickness and a computer loaded with simple spreadsheets
to process tree data (see www.mtg.unimelb.edu.au/tools.htm).
Spray cans of paint, pegs or marking tape are useful for permanently
marking plots for re-measuring over time.
Measuring a single tree
Diameter
Height
Tree Basal
area
Stand
Basal Area
Tree Form
Standing tree
volume
Estimating log
volume on the ground
Measuring a forest of trees
Location, area
and type of forest
Establishing
sample plots
Stand measurements
Stocking Rate
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