Australian Vegetation Attribute Manual

National Vegetation Information System, Version 6.0
Executive Steering Committee for Australian Vegetation Information (ESCAVI)
Department of the Environment and Heritage, 2003
ISBN 0 642 54953 2

Section Three (continued): List of NVIS Attributes

Descriptions of NVIS Attributes (continued)

Map Unit Level Attributes

Reference Information

Attribute: MU01 - MAP UNIT IDENTIFIER
Heading Details
Purpose: The purpose of this attribute is to identify the vegetation description data relating to each spatial unit, so that it can be linked to the spatial coverage.
Requirement: Mandatory
Database Field Name: MAPUNT_IDENTIFIER
Description: A unique map (spatial) unit identifier, which links map units to the data set identifier (DATA_SET_NUMBER) and the vegetation descriptions within them. Up to 6 vegetation descriptions are allowed per map unit. (Map units with more than one vegetation type within them are called mosaics).
Value: Number(10); in the format SDDNNNNN, where S=State code, DD=dataset number within the state and NNNNN = the mapunit ID supplied by the States and Territories. S and NN are assigned by the administrator.
Example: 76017501
Comments: The MAP_UNIT table is essentially the table used to resolve the many to many relationship between the SPATIAL_ATRIBUTE_FORMAT and VEG_DESCRIPTION tables. The map unit can be thought of as an item in the legend of a vegetation map.
Status: Implemented in the NVIS Oracle database.
Descriptive Information

Attribute: MU02 - SPATIAL MIX
Heading Details
Purpose: To specify the spatial mix of a map unit.
Requirement: Mandatory
Database Field Name: SPATIAL_MIX
Description: This attribute provides general information on both the spatial extent and makeup of the discrete sub-associations or floristic groups within the one map-unit. Map units may be homogeneous (pure) or mixed (mosaics).
Spatially mixed map units are defined as those that have a number of discrete vegetation types within a map unit boundary.
Value: Character(50); This is a value set from a defined lookup table. The values in the lookup table are set by the administrator and cannot be added to.
Example: Examples of spatially mixed map units (mosaics):
1. Structurally similar but floristically different vegetation types within one map unit. For example some alpine eucalyptus forests of similar structure but different species mixes may not readily be separable by either API or image classification (without resort to secondary information such as elevation or aspect).
2. Structurally and floristically different vegetation types within one map unit that are not uniquely tied together ecologically (eg. are part of the patterning of the landscape). Most mapped units (depending on scale, interpretation materials, operator efficiency etc.) will be variations on this theme. Vegetation types smaller than the minimum-mapping unit will also occur here.
3. Structurally and floristically different vegetation types within one map unit that are uniquely tied together ecologically. These Community Complexes are defined as vegetation types that occur with other vegetation types that are uniquely tied together ecologically, but are quite different structurally and floristically, but are mapped within map unit (eg. dune and swale complexes).
Comments:  
Status: Implemented in the NVIS Oracle database. Action required by NVIS collaborators to resolve mosaics.
Look-up Table for: SPATIAL MIX
Code Explanation
pure The map unit has only one sub-association or discrete floristic group, and this can be adequately described.
dominant mosaic The map unit has 2 or 3 main sub-associations or floristic groups, one of which occupies or is estimated to occupy greater than 70% of the spatial area of the polygon.
mosaic The map unit definitely has 2 or 3 main sub-associations, which can be described in detail, the spatial extent of each within the polygon is known, and one of the sub-associations is clearly spatially dominant.
equal mosaic The map unit has two or three main sub-associations, which can be described in detail, and the spatial extent of each within the map unit, is more or less equal.
incomplete The map unit definitely has more than one sub-association, although only one can be adequately described.
mosaic unknown The map unit definitely has two or three main sub-associations, which can be described in detail, although the spatial extent of each is unknown.
unknown unknown
Attribute: MU03 - MOSAIC TYPE
Heading Details
Purpose: To specify the data model or format used in describing a mosaic spatial unit. This assists with the matching of source codes to NVIS descriptions.
Requirement: Commonwealth
Database Field Name: MOSAIC_TYPE
Description: Mosaics are defined as heterogenous spatial units, containing more than one vegetation association within the unit of mapping. The field can have one of three values, as per the lookup table, below. 'Unknown' is not a valid option.
Value: Character(1)
Example: M
Comments: This is a new data management field which arose as part of the restructure (2001-02) process.
Status: Implemented in the NVIS Oracle database.
Look-up Table for: MOSAIC TYPE
Code Explanation
S SPLIT - The components of the mosaic are clearly identified within the map unit by the source codes of its constituent elements.
C COMPOUND - The source code for the mosaic as a whole is identical to the codes for all of its constituent associations (as specified within NVIS).
M MIXED - The source code for the mosaic as a whole is not identical to the codes, for some or all of its constituent associations (in NVIS). I.e. this is a mixture of the two above options.
Attribute: MU04 - NUMBER OF VEGETATION DESCRIPTIONS
Heading Details
Purpose: To count the number of discrete vegetation descriptions occurring within the map unit.
Requirement: Essential
Database Field Name: NUMBER_OF_VEG_DESCRIPTIONS
Description: This attribute provides a quick summary of the number of discrete vegetation descriptions occurring within the one map unit. It is a simple sum of the number of discrete vegetation descriptions occurring within the map unit.
Map Unit has one discrete sub-association = 1
Map Unit has two discrete sub-association = 2
Value: Number(10)
Example: 3
Comments: This field checks the integrity of the relevant records in the VEGETATION_DESCRIPTION table through relevant rules (see Section 4).
Status: Implemented in the NVIS Oracle database.
Attribute: MU05 - VEG DESCRIPTION POSITION
Heading Details
Purpose: To document the relative areas or proportions of each vegetation description within the map unit.
Requirement: Essential
Database Field Name: VEG_DESC_POSITION
Description: Each discrete vegetation description (ideally sub-associations) within the map unit is assigned a unique number. The vegetation description with the greatest area must be assigned a value of '1'.
The number assigned to the remaining sub-associations (if they exist in the unit) should be allocated according to decreasing spatial area. Where there is no clear pattern of spatial dominance for subsequent sub-associations, the numbering can be arbitrary.
Value: Number(10)
Example: 3
Comments: This is a new field which arose as part of the restructure (2001-02) process. It is similar in intended function to the obsolete field VEGETATION DESCRIPTION NUMBER in the VEG_DESCRIPTION table.
Status: Implemented in the NVIS Oracle database.
Attribute: MU06 - VEG DESCRIPTION PROPORTION
Heading Details
Purpose: To document the estimated percentage area of each vegetation description within the map unit.
Requirement: Optional
Database Field Name: VEG_DESC_PROPORTION
Description: Percentage of each vegetation description.
Value: Number(10)
Example: 40
Comments: This is a new field which arose as part of the restructure (2001-02) process.
Status: Implemented in the NVIS Oracle database.