This project will focus on grass-stabilized sand dunes and loess landscapes (areas of thick wind-blown dust deposits) in the Great Plains, to determine how processes that shaped these landscapes in the past will influence their response to future climate change, especially more frequent severe drought or heavy rainfall. The research will test whether soil formation over hundreds to thousands of years, including accumulation of organic matter and fine dust, can significantly reduce the susceptibility of certain parts of these landscapes to wind and water erosion. The results will be important for predicting patterns of future accelerated erosion and dune activation, with major practical implications, since the level tablelands of the loess landscapes are prime agricultural land and the dunes are important rangeland and key recharge areas for the Ogallala Aquifer. Increased erosion could also affect sediment input to streams and release carbon stored in buried and surface soils in these landscapes. The project will provide research training to a diverse group of students and will include development of effective ways to communicate the results to local communities and other stakeholders.
The project will test hypotheses on the interactions between geomorphic processes and soil formation in the evolution of loess tablelands and adjacent dune fields. The hypotheses propose that aeolian processes (deflation, slow loess accumulation, and dune activity) influence spatial patterns of soil formation and organic carbon accumulation, which in turn influence thresholds for wind and water erosion through effects on vegetation resilience and mechanical strength. Study sites will be selected to allow comparison of soil and sediment properties related to nutrient and water availability and shear strength on tableland summits and adjacent slopes with varying soil development and recent loess accumulation, and on dunes with varying soil development. Field and lab measurements will be combined with modeling of soil hydrology, geospatial analyses, and luminescence dating.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.