Mapping change in key soil properties due to climate change over south-eastern Australia

Climate change will lead to altered soil conditions that will impact on plant growth in both agricultural and native ecosystems. Additionally, changes in soil carbon storage will influence carbon accounting schemes that may play a role in climate change mitigation programs. We applied a digital soil mapping approach to examine and map (at 100-m resolution) potential changes in three important soil properties - soil organic carbon (SOC), pH and sum-of-bases (common macro-nutrients) - resulting from projected climate change over south-eastern Australia until similar to 2070. Four global climate models were downscaled with three regional models to give 12 climate models, which were used to derive changes for the three properties across the province, at 0-30 and 30-100 cm depth intervals. The SOC stocks were projected to decline over the province, while pH and sum-of-bases were projected to increase; however, the extent of change varied throughout the province and with different climate models. The average changes primarily reflected the complex interplay of changing temperatures and rainfall throughout the province. The changes were also influenced by the operating environmental conditions, with a uniform pattern of change particularly demonstrated for SOC over 36 combinations of current climate, parent material and land use. For example, the mean decline of SOC predicted for the upper depth interval was 15.6 Mg ha(-1) for wet-mafic-native vegetation regimes but only 3.1 Mg ha(-1) for dry-highly siliceous-cropping regimes. The predicted changes reflected only those attributable to the projected climate change and did not consider the influence of ongoing and changing land management practices.