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Woody Age Since Disturbance - Sentinel-2, DETSI Algorithm, QLD Coverage 

Ver: 1.0
Status of Data: completed
Update Frequency: annually
Security Classification: unclassified
Dataset Published: 2023-11-03
Dataset Last Modified: 2026-08-18
Metadata viewed 271 times
Dataset accessed 77 times
Metadata Created: 2023-10-09
Metadata Last Modified: 2026-08-18
How to cite this collection:
Department of the Environment, Tourism, Science and Innovation, Queensland Government (2023). Woody Age Since Disturbance - Sentinel-2, DETSI Algorithm, QLD Coverage. Version 1.0. Terrestrial Ecosystem Research Network. Dataset. https://portal.tern.org.au/metadata/9e835aec-5314-42c4-a39a-c8ef5959c12c 
Data can be accessed from the following links:
HTTPCloud Optimised GeoTIFFs - Woody Age Since Disturbance - Sentinel-2
WMSwoody_age_since_disturbance
HTTPLandscape Data Visualiser - Woody Age Since Disturbance - Sentinel-2
HTTPPoint-of-truth metadata URL
HTTPro-crate-metadata.json
The woody vegetation extent for Queensland is attributed with an estimated age in years since the last significant disturbance. The method uses a sequential Conditional Random Fields classifier applied to Landsat time series starting 1988 to predict woody cover over the time period. A set of heuristic rules is used to detect and track regrowing woody vegetation in the time series of woody probabilities and record the approximate start and end dates of the most recent regrowth event. Regrowth detection is combined with the Statewide Land and Trees Study (SLATS) Landsat historic clearing data to provide a preliminary estimate of age since disturbance for each woody pixel in the woody extent. The 'last disturbance' may be due to a clearing event or other disturbance such as fire, flood, drought-related death etc. Note that not all recorded disturbances may result in complete loss of woody vegetation, so the estimated age since disturbance does not always represent the age of the ecosystem. The age since disturbance product is derived from multiple satellite image sources and derived products which represent different scales and resolutions: Landsat (30 m), Sentinel-2 (10 m) and Earth-i (1 m). 
Credit
We at TERN acknowledge the Traditional Owners and Custodians throughout Australia, New Zealand and all nations. We honour their profound connections to land, water, biodiversity and culture and pay our respects to their Elders past, present and emerging. 
Purpose
To provide an estimation of woody vegetation age for ongoing monitoring and reporting. 
Lineage
Data not provided. 
Method DocumentationData not provided.
Procedure StepsData not provided.
Spatial Description
Queensland 
Temporal Coverage
From 1988-01-01 to 2022-12-31 
Spatial Resolution

Distance of 10 Metres

Vertical Extent

Data not provided.

Data Quality Assessment Scope
Completeness (omission):
  • The dataset is unvalidated against field measures of vegetation age.
  • There are some limitations to the age since disturbance estimation. It is assumed that the SLATS clearing data always records a transition from woody to non-woody, however, the Landsat clearing record does contain partial clearing. Additionally, the woody extent baseline contains sparse and/or young woody vegetation that may not have been detectable by Landsat - either by the Conditional Random Fields Landsat time series modelling or by SLATS in previous reporting periods and was therefore not able to be monitored at that scale. Missing data in the CRF fractional cover model inputs due to persistent cloud or topographic shadow as well as real but transient disturbance events such as fire or flood may cause woody probabilities to fall to 0, confounding regrowth age estimation.

Consistency (conceptual):
  • The dataset is unvalidated against field measures of vegetation age.
  • The woody mapping specifications differ between the woody extent mapping data set and the SLATS Landsat clearing record. The 2018 woody extent baseline captures woody vegetation greater than 0.5 ha with a crown cover greater than ~ 10%, whereas the SLATS Landsat-based clearing data sets record clearing in woody vegetation > ~ 20% crown cover (minimum mapping unit of approx. 0.25 ha). This means that historic clearing events in some sparsely vegetated < 20% crown cover (~10% FPC) may not have been recorded by Landsat, and the age since disturbance therefore may be over-estimated in these regions. Integration of data sets of varying mapping scales and different resolutions derived from Landsat (30 m), Sentinel-2 (10 m) and Earth-i imagery result in some inconsistencies due to scale effects. The minimum mapping specifications of 0.5 ha in the woody extent means that small, nonwoody gaps (< 0.5 ha) and narrow linear features such as some roads and easements are labelled woody in the woody extent and may therefore be attributed with an age > 0. Conversely, small woody patches (< 0.5 ha) are labelled non-woody and will be assigned an age of 0 years.
 
Data Quality Report
Data not provided. 
Data Quality Assessment Outcome
Data not provided. 
ANZSRC - FOR
Environmental management
Data Stream
Satellite Remote Sensing
GCMD Sciences
VEGETATION - VEGETATION COVER
Horizontal Resolution
30 meters - < 100 meters
Instruments
MSI
OLI
Parameters
disturbance age
Platforms
earth observation satellite
Sentinel-2A
Sentinel-2B
Project
TERN Landscapes
Temporal Resolution
Annual
Topic
environment
imageryBaseMapsEarthCover
Author
Department of the Environment, Tourism, Science and Innovation, Queensland Government
Contact Point
Data Enquiries, Earth Observation and Social Sciences (EOSS)
Publisher
Terrestrial Ecosystem Research Network
Terrestrial Ecosystem Research Network
80 Meiers Road, Indooroopilly, Queensland, 4068, Australia.
Contact Us
Creative Commons Attribution 4.0 International Licence
https://creativecommons.org/licenses/by/4.0/
The Creative Commons Attribution 4.0 International (CC BY 4.0) license allows others to copy, distribute, display, and create derivative works provided that they credit the original source and any other nominated parties. Details are provided at https://creativecommons.org/licenses/by/4.0/ 
Please cite this dataset as {Author} ({PublicationYear}). {Title}. {Version, as appropriate}. Terrestrial Ecosystem Research Network. Dataset. {Identifier}. 
TERN services are provided on an "as-is" and "as available" basis. Users use any TERN services at their discretion and risk. They will be solely responsible for any damage or loss whatsoever that results from such use including use of any data obtained through TERN and any analysis performed using the TERN infrastructure.
Web links to and from external, third party websites should not be construed as implying any relationships with and/or endorsement of the external site or its content by TERN.

Please advise any work or publications that use this data via the online form at https://www.tern.org.au/research-publications/#reporting 

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