Vegetation Extent Monitoring

​​Monitoring Vegetation Extent Program (MVEP)

The Monitoring Vegetation Extent Program (MVEP) has, as its main objective, the improvement of the State’s ability to report on vegetation indicators. A particular emphasis is placed on reporting against the sustainability indicators listed in the Tasmanian Regional Forest Agreement (RFA) and expressed in the five-yearly State of the Forests reporting document.

The MVEP aims to identify areas of native vegetation that are considered to have changed from woody cover to non-woody cover (e.g. from eucalypt forest to pasture, urban or water) within a nominated time period (e.g. five years). Over time, the changes detected by MVEP are also used to prioritise areas of TASVEG mapping that require updated community codes.

The MVEP identifies areas of woody change through the automated comparison of satellite imagery, with extensive desktop validation undertaken using higher resolution imagery and ancillary datasets. Field validation is not currently undertaken, and no attempt is made to identify the cause of change observed. The identification of change polygons within the MVE data is limited to priority areas, which largely correspond to the private land estate of Tasmania.

The MVEP primarily uses Landsat and Sentinel 2 imagery to identify areas of change. NRE has pursued partnerships with the Commonwealth and Queensland governments to secure the future of the MVE program. The tools and outputs generated via these partnerships are based on rigorous scientific research and provide the Tasmanian Vegetation Monitoring and Mapping Program (TVMMP) with the capability to analyse vast quantities of imagery without costly investment in IT infrastructure.

The current method for detecting woody change in Tasmania closely follows the procedures outlined by the Queensland SLATS program​ (program partners). Whilst the SLATS techniques are broadly applicable to the Tasmanian environment they are not perfect and areas of woody change are not always detected e.g. due to persistent cloud cover. TVMMP utilises its partnership with SLATS to stay up to date with the latest advancements in remote sensing techniques for woody change monitoring.

As MVEP change polygons are not currently field verified, the reliability of the outputs aren’t as high as described by the SLATS methodology. For this reason, and because the entire state is not yet routinely analysed, MVEP change data is not normally published as a stand-alone item. Change data does however flow through to TASVEG mapping.​​

Sentinel 2 background image showing woody clearing between two dates different dates of capture 

The picture above highlights woody change detection related to the construction of a new dam and reservoir. The left image was captured by Sentinel 2 on 14/02/2017 and the right image was captured on 21/12/2019. The white polygons highlight areas of woody removal, and the purple polygons highlight areas of woody disturbance (thinning of woody material, without conversion of the TASVEG community). These polygons were detected using Landsat imagery (30m pixel size). Planned future capture using Sentinel 2 imagery (which has a pixel size of 10m) will allow for greater accuracy in delineating woody change boundaries.​