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System Title

5.17 New Zealand Land Resources Inventory Classification Including Land Use Capability Units
Keywords rock type; soil classifications; slope; erosion; vegetation; land use capability; primary production; soil conservation; erosion control; digital terrain models  
Description The New Zealand Land Resources Inventory (NZLRI) divides the New Zealand landscape into land use capability units (map polygons) and provides a national database of physical land-resource information, based on two sets of data:
  • An inventory of five physical factors basic to the assessment of land resources:
    • rock type
    • soil type
    • slope
    • erosion degree and type
    • vegetation
  • A Land Use Capability (LUC) rating of each unit (map polygon) based on an assessment of the ability that unit to provide sustained agricultural production. This included an assessment of:
    • the five physical factors above
    • climate information
    • effects of past land use
    • potential for erosion

While the units are relatively 'homogenous' at the scale of mapping (i.e. 1:63 360 and later 1:50,000, they (polygons) were defined firstly on rock type and slope. This means that there is often variability for some factors. especially vegetation, within the units.

Each unit contains information about:

  • each of the five physical factors
  • the LUC classification

The inventory and capability classification mapping process included aerial photograph interpretation and field work. The assessments of the five physical characteristics were based on relatively objective field and other measurement, while the LUC class identifications were interpreted from a range of information sources.
Original Purpose New Zealand land resource surveys were originally carried out to assist the National Water and Soil Conservation Organisation to fulfill its responsibilities for soil conservation and erosion control. After 2 -3 decades of catchment scale LUC mapping, it became apparent that a nationally coherent approach was required for physical land resource mapping.

The Land Use Capability Classification System was designed to assist practitioners to better target and communicate soil conservation and erosion control work.
Status The status of the NZLRI, which contains the LUC classification, is as follows:
  • first edition 1973 - 79 (except for Stewart Island)
  • South Auckland remapped in the early 1980's
  • Northland Peninsula re-mapped late 1980's
  • Awatere, Clarence, Wairau catchments remapped late 1980's
  • Wellington - south of Manawatu River and down eastern side of Tararuas, remapped early 1990's
  • Gisborne District Council area remapped mid to late 1990's
Organisation Manaaki Whenua Landcare Research is the custodian.
Jurisdiction New Zealand
Contact person/position Peter Newsome
Address Manaaki Whenua Landcare Research
Private Bag 11052
Palmerston North
Phone +64 (6) 3567154
Facsimile +64 (6) 3559230
Email: Newsomep@landcare.cri.nz
Available format NZLRI information is made available to users in three ways:
  • hard copy NZLRI worksheets
  • hard copy extended legends that accompany the work sheets
  • digital ARC/Info GIS maps and accompanying legends
Access Access is through Manaaki Whenua Landcare Research with individual agencies retaining hard copy and digital information relevant to their area jurisdiction for their own use.

Hard copy and/or digital information can be purchased from Manaaki Whenua Landcare Research. Costs vary depending on whether:

  • primary data is already available and in GIS format
  • new coverage and/or reinterpretation of existing data is required.
Geographical coverage National (excluding Stewart Island and offshore islands)

 

Operational Specifications

  
Scale of Operation The inventory factors and LUC assessments are mapped in the NZLRI at a scale of 1:63,360 (first-edition) and 1:50,000 (second-edition).

Second edition inventory map polygons have a minimum size that represents 6.25 ha on the ground.
GIS Compatibility Yes
Relationship between levels in the classification system

LUC assessments are made in a three-part hierarchy as follows:

  • LUC class - this is the first and broadest category. It expresses the total degree of limitation to sustained use. There are eight LUC classes used in New Zealand, from class 1 (negligible limitation) to class VIII (extreme limitation).
  • LUC subclass - the second category. Expresses the major kind of limitation. There are 30 LUC subclasses in New Zealand. The NZLRI uses four LUC subclass limitations:
    • erosion (e)
    • wetness (w)
    • soils (s)
    • climate (c)
  • LUC unit - the third and most detailed category. Each LUC unit is defined by its unique assemblage of physical factors. A LUC unit groups uniform land types together. Specifically, a LUC unit will group map polygons which 'respond similarly to the same management; are adapted to the same kinds of crops, pasture or forest species; have about the same kind and intensity of soil conservation and other land management measures'. (Jessen et al, 1999). There are over 700 LUC units in the NZLRI. They are therefore much more useful for detailed planning than the LUC class or subclass. A LUC unit is indicated by an Arabic number placed after the subclass limitation symbol (e.g. VIe1)

Each of the 12 NZLRI regions has a unique set of LUC units. For example, VIe1 in the Waikato region is specific to that region, and different from V1e1 in the Wellington region. Page (1985) correlated LUC units from the first-edition regional classifications of the North Island, by grouping together LUC units that are essentially the same, but in different regions, to help users who are working across NZLRI regional boundaries.

In a classification of LUC units, the numerical ranking of units based on decreasing versatility and capability gives no direct indication of relationships between LUC units in their landscape setting. To enable these relationships to be better understood and help interpret LUC maps, related LUC units are arranged into groups, called LUC suites. A LUC suite is 'a group of LUC units which, although differing in capability, share a definitive physical characteristic which unites them in the landscape'. (Jessen et al, 1999). These characteristics may vary from suite to suite.
Contributing databases/ classification systems The inventory of physical factors is obtained by reference to pre-existing information, field verification, and stereoscopic interpretation of vertical aerial photographs.

Data sets from a range of sources are drawn together and interpreted to build up a charactarisation of each factor.

Rock type: a rock type classification has been developed to suit the requirements of the NZLRI. This classification groups rocks with similar erosion susceptibilities and characteristics, and concentrates on those rocks that directly influence surface morphology and land use.

Soil: soil information is normally obtained from existing soil surveys, and field checks are used to validate the information. Where soil data are not available at an appropriate scale, physiographic analysis is used to re-interpret small-scale information to fit the 1:50 000 scale. The development of soil-landscape models (McLeod et al. 1995) and use of the New Zealand Soil Classification subgroups (Hewitt 1998) has greatly improved soils information.

Slope: Slope is classified into eight groups, e.g. A (0-3°) to H (> 42°). These are based on broad land management criteria (e.g. the use of wheeled vehicles is appropriate up to and including slope C; cultivation for cropping by vehicles is not possible in slope E and steeper.

Erosion: Fifteen erosion types are recorded. Up to four types are recorded in each map polygon and a severity ranking is applied to each type. The area of the map polygon affected by erosion is the main consideration when assessing erosion severity for most types.

Vegetation: for NZLRI vegetative-cover mapping, emphasis was placed on identifying important species and associations rather than on providing a botanical classification. Classes are recorded in five broad vegetation cover groups: grass, crops, scrub, forest and herbaceous. Many polygons therefore record vegetation associations based on proximity rather than ecological relationships.

Climate: unlike other factors, climate is not mapped. However, broad climatic factors are recognised in many LUC units, especially the arable ones.
Contributing database GIS compatibility Yes
Relationship with other classification systems and spatial frameworks. Uses soil classifications produced by the former New Zealand Soil Bureau. Each survey is referenced in the worksheet.

Taranaki Regional Council Sustainable Land Use Classification is based primarily on the NZLRI LUC assessment.

Environment Bay of Plenty proposed framework for monitoring soil intactness and soil health identifies land management suites which are based on NZLRI units.

Environment Bay of Plenty proposed framework for monitoring ecological integrity uses land systems based on LUC units.

Otago Regional Council Land Management frameworks is based on NZLRI LUC assessment.
Relationship with other databases NZLRI and NZ Soils Database are two separate systems that can interact.

 

Current and emerging use for:

  
Assisting with determining historic state/ baseline Provides a baseline of physical factors and LUC for primary production, as at the time of mapping (recent historic state).
Assisting with determining current state/ baseline Re-mapping of erosion and vegetation of areas may provide an indication of change from this baseline, but would need to be targeted. It may be possible to update information on vegetation and erosion using satellite imagery, aerial photography and recent forestry company maps. GIS could then be used to analyse changes.

Limitations associated with the original vegetation mapping may limit the potential for use of the LRI in this way unless the original areas are remapped. This has occurred in the Gisborne Region where the NZLRI and LUC maps can be used to assess current state/baseline.
Asssisting with scenario building and modelling of possible futures Inherent in LUC Classification.

With intelligent use (i.e. taking into account underlying assumptions) of LUC it is possible to predict the potential effects of land use changes for erosion and soil health in identified areas.
Risk Assesment Yes see:
  • Taranaki Regional Council
  • Otago Regional Council
  • Environment Bay of Plenty
Monitoring site selection and sample design Yes see:
  • Taranaki Regional Council
  • Otago Regional Council
  • Environment Bay of Plenty
Aggregating and reporting data locally, regionally and/or nationally It should be possible to aggregate data by LUC Class at one of the three levels (class, sub-class, unit) (appropriate level will depend on purpose) and report by region or nationally. For example, erosion could be reported by Class and Sub-class (such as by VIIe). This would be dependent upon correlation of LUC units between the different regions being completed.

It would not be appropriate to aggregate vegetation data classified using the NZLRI system, unless the unit of vegetation data storage matches the vegetation boudaries rather than rock type/slope unit boundaries.

Current use (who,level,why)

NZLRI is present in either hard copy or GIS format in the following agencies:

It has primarily been used by regional councils (and their predecessors) as a basis for guiding soil conservation and related land management functions.

Jessen et al (1999) note that the NZLRI database can be used in two ways:

Secondary interpretations are those where the NZLRI intersects with other databases, or where new knowledge from other sources is added, to establish what is essentially a new interpretation. E.g.:

(Jessen, et al. 1999).

A number of regional and district councils/unitary authorities have attempted to use the NZLRI and LUC as a basis for rules within statutory plans. It has worked well as a planning tool for indicating a certain type of rule set should apply, but has provided less successful where it has been used without due consideration of scale and other limitations associated with the underlying data (e.g. where 1:50 000 data is applied at 1:1 scale without a site inspection to confirm what is actually on the ground). LUC needs to be re-interpreted at the scale of activity under consideration.

User friendliness/public and decision maker understanding

System strengths

Current limitations of system

Users making primary interpretations for LUC-based inquiries should understand the principles of the LUC system, the limitations of scale, the limitations associated with the vegetation classification and mapping, and the significance of the time of data collection to changeable factors such as vegetative cover and erosion. Where these are not recognised by users, the use of the NZLRI database may be seen as inappropriate. (Jessen et al, 1999).

Application by inexperienced staff can lead to debates (sometimes in the Environment Court) which could have been avoided.

The primary use of the NZLRI database is limited by the recorded factors, however there is potential for a range of secondary uses. Nevertheless, the following limitations need to be recognised to eliminate inappropriate uses:

It is implicit in mapping that the information recorded will not adequately describe some parts of the map polygon. A rule-of-thumb assumption for users of the information is that up to 20% of any map polygon might be poorly described.

Therefore, it is important to avoid using NZLRI data at scales large than the original mapping scale because the inherent non-representative parts of a map will be enhanced. When information is sought for areas that are best represented by larger mapping scales, or for site interpretations, data are best gathered separately from the NZLRI maps (still using these maps as a guide), e.g. as for farm planning.

There are no longer budgets available for training and education of practitioners wishing to use the NZLRI and LUC Classification system.

There are a number of limitations associated with the contributing data. These include:

References

Jessen, M.R., Crippen, T.F., Page, M.J., Rijkse, W.C., Harmsworth, G.R., McLeod, M. 1999. Land Use Capability of the Gisborne-East Coast region. Landcare Research Science Series No.21. Water and Soil Division, Ministry of Works and Development. 1979. Our Land Resources. A Bulletin to Accompany New Zealand Land Resource Inventory Worksheets.