Glossary of terms used in national exotic forest description reports

Age: The ages of forest areas are as at 1 April of the survey year. A forest area is age one as at 1 April 2010 if it was planted in the preceding 12-month period; for example, between 1 April 2009 and 31 March 2010.

Confidentiality: Values are considered confidential if the number is made up of fewer than three contributors’ information or where one owner’s data makes up more than 80 percent of the value of that number. Forest owners are asked whether they are prepared to waive these strict confidentiality criteria in relation to the data they supply. If a number does not meet the confidentiality criteria and one of the contributors to the confidential number is not prepared to waive the confidentiality rules then that number is not published.

Crop type: For the purpose of the NEFD, a crop type is defined as an aggregate of forest stands of the same species group and tending regime located within the same territorial authority area. The crop type definitions are mutually exclusive and include all planted forest areas.

Land cover types prior to afforestation:

  • “Improved pasture” is land that contains improved pasture species and/or has been fertilised.
  • “Scrub” is land predominantly covered in species such as bracken, gorse, manuka, kanuka or other woody plant species.
  • “Unimproved pasture” is land with no improved pasture species and which has not been fertilised.

Net stocked forest area: The planted production forest area occupied by trees excluding mappable gaps such as landings, roads and other unstocked areas.

New planting: The planting of trees for the primary purpose of producing wood or wood fibre, on land that has not previously been used for growing planted production forests.

Planted production forest: An area of trees not less than one hectare in size, planted and managed with the intention of producing wood or wood fibre. In New Zealand almost all planted production forests are made up of introduced tree species. The NEFD survey does not necessarily collect information on individual forests. Instead, it collects the forest area by crop type of all forests administered by each forest owner or manager.

Replanting: The replanting of a planted production forest area that has been clearfelled.

Rotation number:

  • The first rotation is stands of forest planted on land not previously in planted forest.
  • The second and subsequent rotations are stands of forest growing on land from which a previous forest crop has been grown and harvested.

Species group: Six groupings of tree species are used to describe the national planted production forest resource:

  • radiata pine (Pinus radiata);
  • Douglas-fir (Pseudotsuga menziesii);
  • cypress species;
  • other softwoods;
  • eucalyptus species;
  • other hardwoods.

Where a mixture of species is present the area is allocated to the crop type of the dominant species group.

Stand: A defined area of standing trees or forest, usually of one species, age and tending regime.

Standing volume: The total volume (in cubic metres) of wood contained in stems of all age classes. The standing volume includes some non-recoverable volume, but excludes bark.

Tending regime: Radiata pine has four tending regime categories, Douglas-fir two, and other softwoods and hardwoods are not assigned a tending regime.

The radiata pine tending regime categories are:

  • pruned with production thinning;
  • pruned without production thinning;
  • unpruned with production thinning;
  • unpruned without production thinning.

The Douglas-fir tending regime categories are:

  • with production thinning;
  • without production thinning. 

The tending regime is based on the current management, or prior to application of tending, the intention to carry out pruning or production thinning.

“Pruned” refers to pruning carried out before age 12 so that more than 50 percent of the stems in the planned final crop stocking will contain a pruned butt log of not less than four metres in length.

“Production thinning” refers to the extraction of thinnings for commercial use. Stands that have been production thinned produce a smaller clearfell volume than stands that have not been production thinned.

Territorial authority: District and city council areas adopted in October 1989 (see wood supply regions and territorial authorities for more information).

TRVIB: Total recoverable volume inside bark. This is the volume of wood recovered during harvesting, excluding bark, expressed in cubic metres.

Wood supply region: Zones in New Zealand where forest stands of the same species and tending regime are represented by the same generalised yield table. These regions reflect wood supply processing catchments, and reconcile with aggregates of territorial authority units. Ten regions were identified by the NEFD Steering Committee in 1989 (see wood supply regions and territorial authorities for more information).

Yield table: A tabular representation of forest yield in cubic metres per hectare. The yield table is expressed in terms of total standing volume, total recoverable volume and three log type volumes, together with any production thinning volumes by age (one to 80 years). There is a separate yield table for each crop type.

 

Last Updated: 17 December 2010

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