Ecogeomorphology in the Australian drylands and the role of biota in mediating the effects of climate change on landscape processes and evolution

Abstract

Abstract Australian dryland landscape has developed under the influence of aridity, low relief, tectonic stability and biota adapted to nutrient and water scarcity. The biota in general, but notably the plants, mediates the impact of water scarcity and of climate change on ecohydrological and geomorphological processes. It reduce the partitioning of rain into overland flow, and so limit soil erosion, notably through the development of patch structures that partition the landscape into local runoff sources and runon sinks. In large rain events, when flow does reach ephemeral streams, channel-associated plants again modify flow conditions, reducing flow speeds and flow competence. Given the diverse influences of biota on landscape processes, it is argued that it likewise moderated the effects of Quaternary and Holocene climate change. Field evidence from Australian and other drylands suggests that the effect of changing land surface properties on runoff and erosion may exceed the effect of moderate climate change. Knowledge of the role of dryland biota and its role in land surface change is therefore a prerequisite to understanding the responses of landscapes to climate change, to understanding the complex spatio-temporal variability in landscape development, and to developing the ability to correctly interpret the alluvial record of changing geomorphological processes in terms of changes in climate and other external drivers.