Woody vegetation change: Statewide Landcover and Tree Study method

The NSW Government's Statewide Landcover and Tree Study (SLATS) program provides important information to land managers and policy developers about woody vegetation change.

The NSW Government is committed to promoting a thriving, sustainable and resilient NSW. Fundamental to effective natural resource management and comprehensive and reliable decisions is an understanding of landscape scale change.

Satellite images from left to right showing before clearing, after clearing for agriculture and SLATS change detection showing clearing activity in red. 

Understanding woody change detection

The NSW Department of Planning, Industry and Environment Science Division delivers the Statewide Landcover and Tree Study (SLATS) program on an annual basis. 

The SLATS program analyses satellite imagery to detect the location and extent of woody vegetation clearing in NSW from one year to the next. 

SLATS in NSW was adopted in 2006 after being initially developed and implemented in Queensland by the Department of Environment and Science. NSW has since adapted the method to suit current imagery availability and to meet NSW reporting requirements and applications.

Method of detection  

The SLATS program monitors woody vegetation loss by combining automated and manual mapping techniques. SLATS currently uses European Space Agency’s Sentinel-2A and 2B satellite imagery. Previously Landsat 5, 7 and SPOT5 imagery were used.

Process

The automated change ‘detection’ compares two images, ideally captured a year apart in mid-summer. The images have been pre-prepared before comparison to reduce shift and distortion associated with satellite capture.

  1. An automated change detection algorithm is applied to the two images.
  2. This is followed by comprehensive human visual interpretation of areas detected with a high probability of change.
  3. Expert analysts verify the change detection against the pre and post-change sentinel 2 imagery.
  4. Each scene is then peer reviewed before final processing. 

The SLATS program categorises losses of woody vegetation by assigning the vegetation change with a replacement landcover class that indicates the likely purpose for which the vegetation was cleared.

Primary landcover classes

The primary landcover classes are:

  • agriculture e.g. grassland, cropping, horticulture, farm infrastructure
  • infrastructure e.g. residential, commercial, mining, public infrastructure
  • forestry e.g. native and plantation harvesting, establishment, thinning, forestry infrastructure
  • natural processes e.g. fire, landslide, storm, dieback.

More detailed information is provided at Statewide Landcover and Tree Study.

Products

The current and historical SLATS data is made available through the SEED Portal after any compliance investigations for that period have been completed. The resulting statistical analysis is released annually.

Visit Landcover monitoring and reporting for more information.

Historical data is currently delivered in a vector format, from 2015, the data will be delivered as a statewide raster (pixel) product in GeoTiff format. The product indicates where woody vegetation clearing has occurred throughout NSW. 

How are the results used?

Results are used in several ways, including but not limited to the below examples: