The dataset contains maps of total % C₃ and C₄ plant cover, proportional C₃ and C₄ vegetation (relative to combined C₃ and C₄ cover), and vegetation δ¹³C isoscape (stable carbon isotope values) across Australia. Data are centered on year 2015. We used vegetation and land-use rasters to categorize grid-cells (100 m²) into woody (C₃), native herbaceous (C₃ and C₄), and herbaceous cropland (C₃ and C₄) cover. TERN Ecosystem Surveillance field surveys and environmental factors were regressed to predict native C₄ herbaceous cover. These layers were combined and a δ¹³C mixing model was used to calculate site-averaged δ¹³C values.

A total of 53 native Australian species (52x C3, 1x C4) were sampled from 22 plant families and 7 growth forms along a transect in WA spanning 9.56 degrees latitude and 6.85 degrees longitude. Samples were collected using the nationally-accepted AusPlots Rangelands methodology. Samples were stored to preserve isotopic signatures and analysed using standard techniques for mass spectroscopy, including internationally-calibrated standards. Technical replicates of 13% showed very low drift (0.07).