2022–23 SLATS Report

Overview—Mapping and monitoring woody vegetation ecosystems

With an area of approximately 173 million hectares, Queensland is the second largest state in Australia. It is nearly five times the size of Japan and seven times the size of Great Britain. It is home to diverse flora and fauna due to its unique habitats which include extensive arid and semi-arid rangelands, and temperate, sub-tropical and tropical environments.

Queensland has more than 1,400 regional ecosystems with the majority of these described as woody regional ecosystems. These woody regional ecosystems include the sparse and very sparse shrublands and woodlands of the extensive arid and semi-arid rangelands, and the sparse woodlands and mid-dense and dense forests and rainforests along the Great Dividing Range, coastal plains, and in the Cape York Peninsula and Wet Tropics bioregions. These ecosystems play a critical role in supporting biodiversity, maintaining landscape function and water quality, supporting agricultural production, sequestering and storing atmospheric carbon dioxide, and providing recreation and natural amenity. To conserve, protect, and sustainably use these ecosystems in a changing climate, it is essential to have spatial and temporal data and information to characterise their composition and structure and to monitor their dynamics.

In Queensland, the regional ecosystems framework provides the basis for describing the vegetation types and their remnant status. The Statewide Landcover and Trees Study (SLATS) monitors woody vegetation extent, and changes to that extent due to clearing and regrowth, using Sentinel-2 satellite imagery as its primary monitoring tool. A Spatial BioCondition framework has also been developed to characterise and map the condition of the state’s regional ecosystems. Combined, these initiatives provide a spatially and temporally comprehensive account of Queensland’s ecosystems based on peer-reviewed science.

About this report

SLATS aims to describe the woody vegetation that currently exists, and where and how its extent is changing. In 2018, a baseline map of woody vegetation extent was developed. Monitoring and mapping since have focussed on change in woody vegetation extent due to woody vegetation clearing and regrowth. The woody vegetation extent map is then updated, and the changes to the map reported annually. The degree of modification associated with the clearing activity and estimates of woody vegetation density and age since disturbance are also reported.

The 2022–23 SLATS reporting period is nominally from August 2022 to August 2023. A range of data summaries which analyse the clearing and regrowth data with other key data sets of interest and regional summary data for bioregions, are also presented in the report and/or released as Open Data.

The 2022-23 report introduces information about the height of vegetation for areas affected by clearing activity (refer to Statewide breakdown). Clearing activity is summarised by vegetation height based on data from the global canopy height data set published by Lang et al. (2023). This is a 10m spatial resolution estimate of canopy height, based on a model relating Sentinel-2 reflectance to vegetation height data from the space-borne LiDAR from the Global Ecosystem Dynamics Investigation (or GEDI) mission. A preliminary assessment of these data was undertaken using Queensland-based LiDAR data to assess the model’s performance for Queensland. This found that the accuracy was acceptable for the purpose of summarising SLATS clearing activity data by broad height categories. Further research is being undertaken to refine and improve methods to include vegetation height data in SLATS reporting and improve vegetation height spatial data for the state.

Reference: Lang, N., Jetz, W., Schindler, K. and Wegner, J.D. (2023). A high-resolution canopy height model of the Earth. Nature Ecology & Evolution, 7, 1778–1789. https://doi.org/10.1038/s41559-023-02206-6