EAPSI: Does Clay Content in Soil Exacerbate the Effects of Climate Change in Arid Ecosystems?

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Climate change is one of the leading factors behind the range expansion or contraction of species. Through climate models, researchers are able to predict temperature change and rainfall patterns on a local scale. However, to determine what effect these changes will have on plant communities, there needs to be a connection between climate models and in situ plant response variables. The combination of both create species distribution models. In dryland regions of the world where species are currently water-limited, predictive species distribution models are critical to understanding the survival of indigenous plant species in the changing climate. This research will provide information about soil-water-plant relationships, which will be incorporated into predictive models to assess landscape changes in the presence of global climate change. Research will be conducted in collaboration with Dr. John Morgan from La Trobe University in Melbourne, Victoria, Australia.The main question of this research project is: does high clay content in soil increase woody shrub mortality through plant-water stress. This project involves two research aims: 1) spatial sampling of remotely-sensed data, and 2) corresponding field studies. In the field, clay content in critical soil layers, stem water potential of shrubs, soil infiltration, and soil bulk density will be measured. Correlations will be formed between clay content and plant-water stress which will be compared to other dryland regions in the western United States. These data will be added to, and overlayed with, remote sensing images of the area. These results will show how climate change, moderated through the effects of soil clay content, may affect community assemblage in two different dryland ecosystems. These data will inform climate and water models in their prediction for species at risk. Several studies have predicted that shrub distributions will increase with climate change. If shrub increase or decline is linked to precipitation regimes through clay content, inclusive models will be better able to predict areas where shrubs are threatened. This award under the East Asia and Pacific Summer Institutes program supports summer research by a U.S. graduate student and is jointly funded by NSF and the Australian Academy of Science.