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How to measure stem diameter

There are size restrictions that apply to trees that may be cleared (by notification and certification) under the Land Management (Native Vegetation) Code 2018. The below demonstrates how to measure stem diameter, or ‘diameter at breast height over bark’ (DBHOB).

By knowing how to measure stem size, you can be sure to clear safely in accordance with Code prescriptions.

Part 3 Pasture Expansion

Uniform thinning of woody native vegetation (notification and certification)

Allows for the thinning of woody vegetation including trees and shrubs to predetermined densities to provide for improved pasture availability for grazing livestock.

Permitted clearing of native vegetation (summary only - see Local Land Services for a full list of the Code requirements)

(1) Removing native trees and shrubs from a treatment area such that:

(a) the density of remaining native trees and shrubs in the treatment area is the number of stems per hectare specified in the Code,

(b) the retained are, as far as reasonably possible, evenly dispersed, and,

(c) all native trees in the treatment area with a diameter at breast height over bark greater than 90 centimetres are retained

Mosaic thinning of woody native vegetation (certification)

Permitted clearing of native vegetation (summary only - see Local Land Services for a full list of the Code requirements)

(1) Removing native trees and shrubs from a treatment area such that:

(a) the canopy cover of the remaining native over-story in the treatment area comprises at least 30% of the total treatment area,

(b) all native trees in the treatment area with a diameter at breast height over bark greater than 90 centimetres are retained, and

(c) retained native vegetation are, as far as reasonably possible, in patches of at least 5 hectares evenly distributed throughout the treatment area.

Part 2 INS 

Clearing of invasive native species

Managing invasive native species (INS) provides for the removal of listed native species that have reached unnatural densities and have begun to act invasively over an area of land. INS can dominate a treatment area, and so may be cleared to promote regeneration of native vegetation.

Permitted clearing of native vegetation (summary only - see Local Land Services for a full list of the Code requirements)

(1) Clearing is limited to individual plants that are invasive native species, with clearing of non-INS to be to the minimum extent necessary.

Only INS trees with a diameter at breast height over bark of 20cm or less may be cleared, except for the species below, where only INS trees with a diameter at breast height over bark of 30cm or less may be cleared:

  • Callitris endlicheri (black cypress)
  • Callitris glaucophylla (white cypress)
  • E. camaldulensis (river red gum)
  • Eucalyptus intertexta (red box)
  • Eucalyptus populnea (bimble box).

Measuring by tape

The diameter at breast height over bark (DBHOB) is measured 1.3m from the ground. If there are multiple stems on a tree then the diameter is measured on the largest stem.

Figure 1 below shows a simple way of measuring DBHOB. A special DBHOB measuring tape can be used for a more accurate measure. This tree measures a diameter or ‘width’ of 80cm at the height as shown.

Clearing under the Code allows a maximum 90cm DBHOB to be removed for pasture expansion, and a maximum of 30cm for certain INS species.

Figure 1: Measuring diameter at breast height over bark (1.3 metres above ground).

Measuring by string or rope

A specially calibrated diameter tape, sometimes referred to as a foresters tape, displays the diameter measurement when wrapped around the outside (circumference) of a tree. They are not likely to ‘be on hand’ so if you don't have access to one you can still easily find the diameter of the tree using a string or rope, a measuring tape and a calculator.

  1. With the measuring tape, measure 1.3m feet up the trunk of the tree from the ground and mark the height on the tree.
  2. Wrap the string/rope around the tree trunk at the 1.3m height. Make sure the string is straight and tight around the trunk, and mark or cut the circumference on the string/rope.
  3. Now measure the length of string. This will give you the total circumference of the tree.
  4. Now divide the circumference by 3.14 to convert the circumference measurement to diameter.

More information

To find out more about native vegetation and your options under the Land Management Framework:

  • contact Local Land Services on 1300 795 299
  • email slm.info@lls.nsw.gov.au
  • go to lls.nsw.gov.au/slm
  • call in to your nearest Local Land Services office and ask for a Sustainable Land Management officer.

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