Relative Age

dataset: RELAGE
The Statewide Forest Resource Inventory (SFRI) is a program of information collection and analysis of Victoria's native forests that supports statewide planning and management. One SFRI product is SFRImap Database - a database of information on the eucalypt composition, structure and history of Victoria's forests. SFRImap Database covers most of Victoria's forests on public land at a scale of 1:25,000. Relative Age is a layer derived from SFRImap. It is SFRImap dissolved on the RELAGE attribute. Derived layers from SFRImap Database are complimented with the same metadata as the SFRImap layer.
 
Citation proposal Citation proposal

(2022)

Relative Age

Department of Environment, Land, Water & Planning

Description

Title
Relative Age 
Alternate title
RELAGE 
Purpose
Relative Age is a classification based on crown form (not recorded age). For example, forests regenerated after the 1939 wildfires may appear either "Mature" or "Regrowth", even though they originate from the same year. Fire damage may render a stand "Senescent" even if its age is young. "Unevenaged" refers to structurally diverse stands with both regrowth and regular forms. Possible relative ages are: Senescent Late Mature Mature Early Mature Regrowth Regenerating Unevenaged Non-regrowth < 22m Non-regrowth < 28m Undefined 
Credit
The generation of this data set has resulted from the sustained efforts from dedicated professionals from a range of intellectual backgrounds from within DSE and as well as from numerous private organisations. 
Supplemental Information
Relationship to other Datasets: SFRI25BM is the primary layer upon which SFRIMAP derives its linework and attributes. Related Documents: Statewide Forest Resource Inventory: Forest Stand Classification. - Forests Service Technical Reports 00-1 www.dse.vic.gov.au and navigate to Forestry => Info and Research => Statewide Forest Resource Inventory => Stand Mapping www.dse.vic.gov.au/forests/maps&facts/ 
Status
Completed 
 
 

Spatial

Horizontal Accuracy
25m 
Code
4283 
 
 

Maintenance

Maintenance and update frequency
Annually 
 
 

Contacts

  Point of contact

Cited responsible party

No information provided.

Cited responsible party

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Cited responsible party

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Cited responsible party

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Cited responsible party

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Cited responsible party

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Cited responsible party

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Keywords

Topic category
  • Biota
  • Farming
 
 

Constraints

Use limitation
The SFRIMAP layer series data, and its derived layers, is to be supplied only after a data supply request has been approved by the Section Manager (the custodian of the dataset). A data supply agreement may be required. Copyright and disclaimer information must be provided on all digital and hardcopy products using this dataset. 
Classification
Unclassified 
Creative Commons Attribution 4.0 (CC-BY)
 
 

Lineage

Statement
Dataset Source: Linework is derived from SFRI25VE and mapping of forest harvesting and fire. Additional attributes are derived from a range of sources, including historic map records of harvesting and fire of various scales, and well as local verbal advice from expert witnesses. Linework has been generalised with a weed tolerance of 1 metre to reduce layer size and for ease of transfer into SDE. Dataset Originality: Derived 
Description
Collection Method: Aerial photgraph interpretation, ground survey and visual overlay analysis. 
Description
SFRI25VE polygons are attributed with historical fire and logging information, this is referred to as pre-photodate disturbance information. Post-photodate logging history from log_{season} is then unioned in Arcinfo with the interim layer BM25PR which updates the REGEN and TREAT fields according to the silvicultural system used. Significant fire disturbances (e.g. Alpine Fires 2003) are intergrated into the dataset using existing linework. 
 
 

Metadata Constraints Metadata Constraints

Classification
Unclassified 
 
 

Quality

Attribute Quality
Comments
Interpretation of aerial photographs (API) using specialised skills and codes according to Statewide Forest Resource Inventory: Forest Stand Classification (Forests Service Technical Reports 00-1). Initial API audited using a "field based" approach using skilled auditors. Disturbance attributes (REGEN and TREAT fields) rely on the accuracy of disturbance information available. 
 
Positional Accuracy
Comments
The SFRIMAP layer (since being derived from SFRI25VE) is to be used with data sets that are commensurate with the Victorian Government's "VICMAP" 1:25,000 map scale digital map library. The data is designed to be stable for a fuzzy tolerance range of between 0.01 to 10 metres (ground units). Polygons that have the tile boundary included in their perimeter must have at least one vertex greater than 3 meters (ground units) from the tile boundary linework. Internal lines (lines away from the tile boundary must be mort than 10 metres (ground units) away from the next cover so that the maximum deviation between tile boundaries is less than 0.01 metres (ground units). These data limitations are more related to photographic interpretation factors. Any post-photodate intersections with logging history from log_{season} sees the SFRI linework take precendence where snapping has occurred with tile boundaries. 
 
Conceptual Consistency
Comments
Polygon size is related to the type of mapping. All mapped polygon should exceed 5 hectares (ground units). Guidelines as used by DSE for forest stand mapping recommend polygon sizes of between 5 and 20 hectares for "full code mapping" and between 40 and 60 hectares fro "growth stage mapping". Larger polygons may arise due to the forest stand homogeneity. Outlier forested public land is mapped when the area equal to or greater than 5 hectares and the Eucalypt crown-cover class is greater than 2 (ie. crown-cover of less than 30 percent). Where disturbance information has been intersected polygons can occur with minute areas (including slivers up to the weed tolerance level). 
 
Missing Data
Comments
SFRIMAP captures the forests' stages of growth (relative age) in most of Victoria's National parks and State forests. In State forests, more information is recorded - eucalypt species, height, and the utilisation and fire histories - to allow for such tasks as sustainable yield analysis. It also includes the most recent fire and logging information. Areas not covered include the mallee area in Victoria's north west and the Bendigo FMA. Completeness Verification: The forest stand class linework from SFRI25VE, was validated by field checking, and referenced to existing map information and local knowledge. Logging history is derived from 1:25,000 and 1:100,000.mapped information on logging events, aerial photography transferred to 1:25,0000 mapping and other regionally available logging records. Fire history derived from record search, aerial photographs, and regional fire records in the form of fire history maps. 
 
Excess Data
Comments
The major goal of the aerial photograph interpretation (API) phase of the SFRI project was to obtain a comprehensive description of the eucalypt component of the forest. Eucalypt forest was defined as woody vegetation 2 m or more tall and having a eucalypt crown cover of 10% or more of the total forest stand area. The forest stand size for the Full Code mapping type ranged from 1-20 ha with most stands clustered between 10-20 hectares. High contrast forest stands could be as small as 1 ha however a mosaic of small stands with detailed boundary outline was not acceptable. The forest stand outline must be well defined and without the intricate linework that would define individual trees. A balanced approach between detail and stylised linework representative of logical and homogeneous forest units was required. The polygon outline for Growth Stage mapping was reasonably stylised without any sharply defined or intricate detail. The polygon size was generally within the range 40-60 ha. 
 
 
 

Overviews

Graphic Overview of Data Footprint


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