Towards comparability among state-and-transition models: A set of generalised templates linked to ecosystem condition

Suzanne M Prober, Megan Kate Good, Helen Murphy, Alison J O'Donnell, Melissa Piper, Kristen Jennifer Williams, Felipe Albornoz, Shaun Brooks, Jacqui England, Kathryn M Giljohann, Dayani Gunawardana, Sarah Luxton, Beryl Morris, Samantha Munroe, Ellen Rochelmeyer, Ian Warren, Don Butler, nicholas cuff, Fiona Dickson, Josh Dorrough, David Eldridge, Teresa Eyre, Jose Facelli, Brett Howland, Rebecca Jordan, Ashely Leedman, Donna Lewis, Alex Maisey, Sue McIntyre, Tina Parkhurst, Jack Pascoe, Elizabeth Pryde, James Radford, Stephen Roxburgh, Libby Rumpff, Katinka Ruthrof, Rachel J Standish, Ayesha Tulloch, Perpetua Turner, Stephen van Leeuwen, Peter-Jon Waddell, Jessica C Walsh, Michelle Ward, Glenda Wardle, Ian Watson, Mark Westoby, Matt D White, Laura J Williams, Renee Young, Anna Richards

Growing commitments to environmental sustainability and nature conservation by industry, government and communities globally have led to a pressing need for consistent methods to characterise and quantify outcomes of land use and ecological restoration. State-and-transition models (STMs) are widely used to describe and communicate knowledge about ecosystem dynamics and are increasingly applied in such contexts. However, STMs are usually tailored to specific ecosystems and questions, resulting in models that vary widely in character and representation.

To support comparability among STMs and facilitate their application to large-scale environmental initiatives, we collaborated with over 100 ecological scientists, restoration practitioners, and environmental program managers to design a set of generic STM templates and guides. These have already assisted the development of 28 STMs for Australia’s Nature Repair Market and other land management programs, enabling iterative testing and improvement.

Our templates recognise common patterns of ecosystem modification and restoration across terrestrial ecosystems. Three primary templates distinguish an ecologically defining layer from complementary layers, including overstorey versus understorey in forests and woodlands, shrub versus tree or ground layers in shrublands, and ground versus woody layers in grasslands. The templates recognise potential for independent modification or recovery gradients in these layers, leading to a matrix of 16 core ecosystem states, augmented by a set of intensive land-use states. Four secondary templates identify potential finer distinctions within ecological layers. Supporting guides (a) propose a set of attributes for describing states, (b) specify ranges for ecosystem condition scores to guide user allocation of states to the template, and (c) support identification of plausible transitions between states.

Our templates and guides advance state-and-transition modelling by establishing a consistent yet flexible foundation for applying STMs in environmental management programs, environmental accounting, and on-ground ecosystem management. They achieve this by establishing a common framing of ecosystem states linked to ecosystem condition, and aligning with globally-established frameworks. While developed in an Australian context, the templates are adaptable to any terrestrial ecosystem where a historic, climate-adapted or idealised reference state is identifiable. We propose further development to support Indigenous engagement, systematic integration of climate change, and representation of landscape and fauna dynamics.