Frequently Asked Questions for Modelled Native Vegetation Extent Dataset (NV2005_EXTENT)
What is the native vegetation extent dataset?
A model of the current extent of native vegetation across Victoria using time-series LANDSAT imagery together with a number of existing DSE spatial datasets and ground-truthed site data.
Who created the native vegetation extent dataset?
Arthur Rylah Institute for Environmental Research in conjunction with the Ecosystem Services Branch, Biodiversity and Ecosystem Services Division, DSE.
What is the purpose and use of this dataset?
To provide an improved, consistent view of the extent of native vegetation across the whole of Victoria, primarily to inform and assist in native vegetation management and landscape scale planning for biodiversity conservation.
Who is the targeted audience?
Land management agencies across the State, including DSE, Department of Primary Industries, Catchment Management Authorities, Local Government, Parks Victoria and other relevant stakeholders such as Trust for Nature, Greening Australia, Country Fire Authority, universities and consultants.
How was the native vegetation extent dataset derived?
The revised extent layer is a modelled dataset incorporating new and existing models of vegetation cover such as TREE25 (a presence/absence tree cover spatial layer derived from satellite imagery at a scale of 1:25,000) as well as time-series LANDSAT (satellite) imagery, hydropoly25 and hydro25 (line and point features delineating hydrology based on Land Victoria's State Digital Map Base topographic data), Statewide Forest Resource Inventory (SFRI) data, plantations manually created from aerial photograph interpretation plus site-based training datasets consisting of presence/absence data for each of the structural vegetation types based on many thousands of ground-truthing points and expert validation.
Where can I find information on the simplified categories used in the model?
More information on the method used in creating the model and the definitions of the categories used can be found in the metadata document accompanying the spatial dataset.
- For DSE staff access is via the following link: NV2005_EXTENT.
- For external users, access is via this link: Native Vegetation Extent 2005 (25 metre raster) (NV2005_EXTENT)
The map is designed for use at a large scale and has limited use for areas less than one hectare. It contains a set of reliability ratings from “unlikely to support native vegetation” to “highly likely native vegetation” which will assist the user in making an informed decision if unable to ground-truth a site. For site or property-based planning or investment decisions, the dataset is best used in combination with a site assessment to determine the extent of native vegetation at this scale.
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How is the revised native vegetation extent layer different to the existing current EVC extent layer?
The dataset is modelled and only categorises the landscape into native woody, native grassy and native wetland cover with probability ratings of presence of native vegetation rather than using EVC typology. The EVC dataset was created mainly from aerial photography interpretation except for North-Western Victoria whereas the revised native vegetation extent dataset is largely based on satellite imagery.
How do the modelling techniques differ to the previous mapping of native vegetation in Victoria?
Previous mapping had been carried out using a wide range of quality of aerial photography and a variety of assessment techniques at different times over the last decade. The current native vegetation extent map uses satellite imagery and improved biophysical spatial datasets together with more extensive site data, and with the same methodology applied across Victoria.
What are the probability thresholds for native grassland/pasture cover?
The model estimates the presence of vegetation where the perennial cover of native grasses is greater than 50%. The category 'Highly likely' refers to a greater than 66% probability that such vegetation is present, and the category 'Likely' refers to a 50 to 66% probability that such vegetation is present.
What are the differences in native vegetation cover between the 2004 and 2007 datasets?
Improvements in mapping techniques has resulted in the better detection of existing native vegetation (see table below), especially for some extensive areas of lower quality native grasslands amongst pasture in paddocks on private land. This does not reflect areas of new vegetation but areas of vegetation which already existed, but have only now been included in the mapping.
Changes in recorded amounts of native vegetation due to improved detection
| Native vegetation remaining in Victoria (ha) | Dataset | Private land | Public land | Total |
| Previous mapping | (various dates, mostly form 1990's) | 1,370,805 | 6,987,693 | 8,358,498 |
| New mapping | (all the same date - based on 2004/5 imagery) | 3,027,113 | 7,315,358 | 10,342,471 |
How will the native vegetation extent dataset affect the Bioregional Conservation Status (BCS) of existing EVCs?
The Bioregional Conservation Status (BCS) of some EVCs has changed and these are reflected in the updated BCS excel spreadsheet on the DSE Native Vegetation Information for Victoria web page. Each Bioregion home page has also been updated to reflect these changes. Although actual areas of each type have changed, the majority of BCS have remained the same, with only approximately 6% changing status from the 2004 assessment.
What are some of the limitations of the dataset?
The dataset is a good interpretation of native vegetation, but must be used with care, given its modelled nature. It is designed for use at a large scale (1:25,000 to 1:100,000) and is not intended to be used at a site or property scale. Additional ground truthing of sites should be carried out before any planning decisions are made. For example, the model also includes areas of degraded native vegetation which may be due to either loss of overstorey or of understorey.
Is there more information available on this dataset?
Further information on this dataset is available on the DSE Accessing Native Vegetation data webpage: Information Sheet No.3: Native Vegetation Extent Dataset.
How is the Native Vegetation Extent dataset accessed?
- For external agencies, a data licensing agreement with DSE is required by emailing the Data Distribution Manager at data.cgdl@dse.vic.gov.au.
- For DSE staff, access to the dataset (NV2005_EXTENT) is via the CSDL in the following formats:
Format: ESRI grid
Name: NV2005_EXTENT
Library: g500-vg94
Format: Image TIFF
Name: NV2005_EXTENT.TIF
Library: i500-vg94 (Image Web Server)
(The Image Web Server can be accessed via the following link: www.land.vic.gov.au/iwsinfo). Please note: A polygon layer is available in Oracle/SDE.
Who should I contact for more information?
For any queries regarding the content of the native vegetation extent dataset, email the Native Vegetation Information Project Manager: evc.benchmark@dse.vic.gov.au. For queries regarding access to the spatial data, please email the Data Distribution Manager at data.cgdl@dse.vic.gov.au.
back to Accessing Native Vegetation data page
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