A National Exotic Forest Description (2006)
4 Database description
Area database
The base unit for collecting and recording area data is the crop type. Up to ten crop types are recognised for each territorial authority, made up of four tending regimes for radiata pine, two tending regimes for Douglas-fir, and one each for cypress species, eucalyptus species, other softwoods and other hardwoods. For definitions of crop type and tending regime see Appendix 1.
The area data in this database are organised as a net stocked area for each age by crop type, and are labelled with a crop type code and a yield table code.
The area data are rounded to the nearest hectare and are recorded for ages one to 80 years.
The crop type code defines the territorial authority, the species group and the tending regime. The crop type is referenced to a specific table in the yield table database through the yield table code. This cross reference is used to prepare composite databases to calculate estimates of standing volumes. These composite databases are also used for modelling purposes such as wood availability forecasts. For details of such a project refer to NEFD National and Regional Wood Supply Forecasts 2000, MAF 2000.
Yield table database
The yield table database contains yield aggregates of the same species group and tending regime which are located in the same wood supply region. The yield tables contain the total standing volume, total recoverable volume and three log type volumes (pruned logs, unpruned logs and pulp logs), together with any thinning volumes, by annual age class. Each yield table is labelled with a code that defines the wood supply region, species group and tending regime.
Planting and harvesting data
Data have been collected on the area of restocking, new planting and primary land cover before the establishment of forests. The NEFD survey also collects data on clear-felling, including the area clear-felled, the volume yielded and the yield from production thinning for each year ended 31 March (see Table 2.1). The survey also collected data on the volume of clear-felled radiata pine by generalised log grade (pruned logs, unpruned logs and pulp/chip logs).
Other attributes
The NEFD database includes information on forest (meaning trees, not land) ownership type, classified as:
- registered public company;
- privately owned;
- State-owned enterprise;
- local government body;
- central government;
- other forms of ownership.
Each year the NEFD Steering Committee considers the inclusion of any other relevant attributes before requesting data from forest owners.
Land cover database
The location of New Zealand's planted forests as identified in New Zealand Land Cover Database version 2 (NZLCDB2) are shown in Figures 8.1 and 8.2 in this report. Further details about the NZLCDB2 are available on: www.mfe.govt.nz/issues/land/land-cover-dbase/and www.terralink.co.nz/products_services/satellite/land_cover_database_of_new_zealand/
The full NZLCDB2 is available from the data custodians, Terralink International Ltd, as a digital theme ready to import into a geographical information system. The Ministry for the Environment is the steward of the NZLCDB2.
Contact for Enquiries
MAF Information Services
Pastoral House
25 The Terrace
PO Box 2526
Wellington, NEW ZEALAND
Fax: +64 4 894 0721
Contact this person
