Getting ground cover right: thresholds and baselines for a healthier reef. Report to the Reef Rescue Research and Development Program

Abstract

Executive Summary
There is a clear and ongoing need in the Great Barrier Reef (GBR) catchments to quantify changes in the catchment landscape, and to understand how much these changes are driven by climate, management and other factors. This information is fundamental to both risk mitigation on the reef and to ensuring sustainable and productive use of the catchment landscape. Getting ground cover right directly addressed these needs in the Burdekin and Fitzroy natural resource management (NRM) regions of the GBR catchment, developing and distributing landscape monitoring resources for reef catchment stakeholders. These resources included:
• remotely sensed, catchment wide ground cover data;
• spatially validated grazing land condition mapping; and,
• customised monitoring support tools for reef stakeholders.
Project partners have processed over 60,000 Landsat images, converted them to fractional cover imagery and generated a time series of seasonal (3 monthly) cover images for the whole state. The fractional ground cover algorithm developed here estimates ground cover more robustly than its predecessor, and so allows better separation of over storey and ground cover. In addition, we have developed an approach to further separate over storey and ground cover, and developed two tools for distinguishing climatic and management impacts on ground cover levels.