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 Two: The NVIS Framework - Concepts and Standard Procedures (continued)
Each species should be described using full scientific name in the attribute TAXON_DATA_DESCRIPTION in the Taxon_Data table. This field has been retained in this form for operational reasons (rather than split into components, as in the Taxon_Lists table). The onus is on the data supplier to provide consistent spelling and punctuation (e.g. for the infraspecies rank) for the same taxonomic entity. The nomenclature for undescribed species should carry sufficient information to uniquely identify a source collection and location, e.g. Caladenia "Bordertown" (R.S.Rogers 788), rather than "species A" etc. Alternatively, or additionally, the data supplier can provide a TAXON_DATA_SOURCE_CODE, which may be useful in assigning the current taxonomic name to the Taxon_Data record.
Component Data for Species
In a similar way to growth forms, above, detailed source component data about an unlimited number of taxa (species) can be entered into the Taxon_Data table. However, the NVIS Information Hierarchy uses only the top 3 taxa per stratum at Level V and the top 5 taxa per sub-stratum at Level VI. (See the subsection on the NVIS Information Hierarchy and attribute descriptions in the Veg_Description table in Section 3).
It is recommended that the order of the species be to be listed from the most dominant to least dominant using the attribute TAXON_DATA_RANK in the Taxon_Data table. The dominance of a taxon (species) is indicated by its relative biomass in each (sub-)stratum of a vegetation type. The data provider usually estimates the species' biomass as a multiple of cover, height and area covered by the species within the full extent of the vegetation type. Where available, additional data on the type of dominance of the species (or whether the species is an "indicator") in a (sub-)stratum can be recorded in the TAXON_DATA_DOMINANCE_QUALIFIER attribute.
In some cases, where cover and/or height of a species has not been recorded in the field survey, frequency is sometimes used to estimate dominance. However, its use in isolation to estimate dominance is not recommended. The frequency of a species is often reported for a vegetation type and can be recorded in the NVIS database as an independent variable TAXON_DATA_FREQUENCY. It is easily generated from site survey databases as a ratio or percentage of sites containing the species compared with all survey sites.
Detailed cover values can be provided for each species for each (sub-) stratum in the Taxon_Data table. It is important to fill in the COVER_TYPE attribute in the same table.
Where data providers to NVIS want to record the species as sometimes present in the vegetation description, the attribute TAXON_DATA_ALWAYS_THERE in the Taxon_Data should be set to "N". This will provide the raw data for an automated program to generate a "+/-" symbol in front of the species in the vegetation description.
Section 3 provides further details on how species information should be interpreted and entered into the Vegetation_Description and Taxon_Data tables.
Rules for Checking Data and Generating Simpler Levels
At a national workshop in November 2002, the NVIS collaborators agreed to the implementation of proposed rules to address the structural and content issues impacting on the quality and consistency of the NVIS dataset. These include, inter alia, rules to:
- Check the quality and consistency of data between the detailed data tables (Stratum, Growth_Form and Taxon_Data) and the Veg_Description table; and
- Automatically generate the simpler levels in the NVIS Information Hierarchy.
The NVIS collaborators have agreed that conversion from Level VI to V is best undertaken through an expert input, since it is currently too complex to automate the process considering the large variety of methods and data collected. See Section 4 for a description of current progress with the rules.
Putting the Vegetation Description Together
The source component information on growth forms and species can be combined with the structural formation terminology to produce an integrated NVIS Vegetation Description at the complex NVIS level (V and/or VI). The NVIS collaborators have agreed to the use of rules to automate the generation of simpler levels (Levels I to IV) in the NVIS Information Hierarchy.
The rules for generating simpler levels in the NVIS Information Hierarchy require some additional attributes, compared with Version 5.0 of the Attributes (NLWRA, 2000a), to ensure consistent and understandable vegetation descriptions.
One such attribute (the "+" symbol in the Level V and/or VI fields in the Vegetation_Description table and the corresponding value of the DOMINANT_STRATUM_FLAG in the Stratum table) has already been described in the subsection on Stratum Cover and Dominance, above.
When the dominant species and dominant growth form for a (sub-)stratum were used to generate Level IV descriptions by automated rules, anomalies sometimes arose in that the two would not match, - for example, "Eucalyptus fernlands". The anomaly was because Level IV (and III) descriptions are characterised by genus (and not species) and the difficulties in assigning dominance in some vegetation types.
A notation system that is semi-independent from species- and growth form dominance has been devised to ensure consistency in the generation of simpler NVIS levels. The data provider must assign an up-arrow or hat "^" to the genus or growth form believed to best describe and characterise the vegetation type at Levels I to IV (Table 1) in the Veg_Description table. This is usually, but not always, a dominant or co-dominant species or growth form. Then, the matching growth form or genus (i.e. whatever wasn't chosen first) should be tagged with an up-arrow or hat "^". This is Case 1 in Table 5.
A table of possible (i.e. matching) growth forms for each genus has been developed by the NVIS collaborators to enable consistency checking by automated rules. Currently, Rules 29 and 30 in Section 4 implement Case 1.
|Case||Scenario||Genus per stratum (Level V)||Growth Form (GF) per stratum (Level V)||Result||Notes|
|1st hat||2nd hat|
|1||1 dominant /characteristic genus in the stratum||^||-||^||Genus 1 & GF promoted to Level IV (& possibly L III).||
|2||2 co-dominant /equally characteristic genera in the stratum||^||^||^||Genus 1 & 2 & GF promoted to Level IV (& possibly L III).||
|3||3 or more co-dominant / equally characteristic genera in the stratum||^^||-||^||Genus 1, "mixed" & GF promoted to Level IV (& possibly L III).||
- If the stratum is indicated (with a plus '+' symbol) as the dominant in the vegetation type, the genus (or genera) and growth form will also be promoted to Level III.
- Cases 2 & 3 have not yet been implemented in the NVIS database.
- Case 2 has the potential for a genus with unmatched growth form. Thus Rules 12, 13, 14 and 30 will need to be modified.
NVIS collaborators have agreed that in some cases, one genus is inadequate to describe the floristics of some strata at Level IV. Where two genera are necessary to describe a stratum, a second up-arrows or hat "^" can be added to another genus in the stratum. (At Level VI, the genus can be in a different sub-stratum.) The genera will be written out in the Level IV description (and III, if the stratum is dominant: i.e. is marked with a '+' at Levels VI to IV) in the dominance order specified in TAXON_DATA_RANK. This is case 2 in Table 5.
Where more than two genera are characteristic of the stratum, the word "mixed" can be generated at Level IV by the use of a double up-arrow or double hat "^^" on one genus in the Level V or VI description. (If a double hat is used on one genus in a stratum, one genus is written in Level IV with the word "mixed" afterwards.) Only one growth form hat per stratum is permitted and this must match one of the two genera marked with the double hat.
The double hat facility has not been provided for the growth form table, because many growth forms can usually be found in each stratum, if one looks hard enough. In other words, each stratum is "mixed", by default, with respect to growth forms.
This information is also stored in TAXON_DATA_SUMMARY_FLAG in the Taxon_Data table and/or GROWTH_FORM_SUMMARY_FLAG in the Growth_Form table - see Section 3 for details.
Detailed Examples of the NVIS Information Hierarchy
A completed NVIS vegetation description is given in Table 6. Table 6 also summarises the use of each component of the NVIS Information Hierarchy (Table 1) - species, growth form, cover and height. The examples in Table 6 illustrate, for the same vegetation type, the resultant standardised description of the type at various levels in the NVIS Information Hierarchy.
Appendix J gives an example of a complete vegetation description and shows the relevant content of each attribute in the NVIS Database. Please note, in particular, the contents of attributes in the Veg_Description table.
|I||CLASS||-||1 dominant growth form for the dominant stratum||-||-|
|II||STRUCTURAL FORMATION||-||1 dominant growth form for the dominant stratum||1 cover class for the dominant stratum||1 height class for the dominant stratum|
|III||BROAD FLORISTIC FORMATION||1 dominant genus name for the dominant stratum||1 dominant growth form for dominant stratum||1 cover class for dominant stratum||1 height class for dominant stratum|
|Example||Eucalyptus open woodland|
|IV||SUB-FORMATION||1 dominant genus name for each stratum ((max 3 strata; i.e. for U, M, G where substantially present)||1 dominant growth form for each stratum (max 3 strata)||1 cover class for each stratum (max 3 strata)||1 height class for each stratum (max 3 strata)|
|Example||+Eucalyptus open woodland\Acacia tall sparse shrubland\Aristida open tussock grassland|
|V||ASSOCIATION||Up to 3 dominant species for each stratum (max 3 strata; i.e. for U, M, G where present)||Up to 3 dominant growth forms for each stratum (max 3 strata; i.e. for U, M, G where present)||1 cover class code for each stratum (max 3 strata; i.e. for U, M, G where present)||1 height class code for each stratum (max 3 strata; i.e. for U, M, G where present)|
|Example||U+ ^Eucalyptus coolabah,Casuarina cristata,Flindersia maculosa\^tree\7\r;M ^Acacia salicina,Alectryon oleifolius,Acacia stenophylla\^shrub\4\r;G ^Aristida ramosa,Astrebla squarrosa,Bothriochloa decipiens\^tussock grass,forb,sedge\2\i|
|VI||SUB-ASSOCIATION||Up to 5 dominant species for each sub-stratum (i.e. for U1, U2, U3, M1, M2, M3, G1, G2 where present)
||Up to 5 dominant growth forms for each sub-stratum.
||1 cover class code for each sub-stratum||1 height class code for each sub-stratum|
|Example||U1+ ^Eucalyptus coolabah,Casuarina cristata,Flindersia maculosa\Eucalyptus\^tree\7\r;M1 ^Acacia salicina,Alectryon oleifolius ,Acacia stenophylla,Acacia victoriae subsp. victoriae,Eremophila bignoniiflora\Acacia\^shrub\4\bi;M2 Eremophila longifolia,Muehlenbeckia florulenta\Eremophila\shrub\3\r;G1 ^Aristida ramosa,Astrebla squarrosa,Bothriochloa decipiens,Dichanthium sericeum,Enteropogon acicularis\Aristida\^tussock grass,forb,sedge\2\i|