Collaborative Research: On Topographic Imprint of Hillslope Aspect: Deciphering Aspect Controls on Vegetation and Landforms in Central New Mexico

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Collaborative Research: On Topographic Imprint of Hillslope Aspect: Deciphering Aspect Controls on Vegetation and Landforms in Central New Mexico This project will investigate the role of aspect and vegetation in modulating rates and processes of landscape evolution in desert elevations of central New Mexico, where aspect plays a dominant role on ecosystem structure. The influence of vegetation patterns on runoff and erosion have been studied in semiarid ecosystems, especially in the Long Term Ecological Research sites in the southwest US. Research has identified critical concerns about the landscape scale impacts of vegetation change, and resulted in testable hypotheses. Yet, long-term implications of vegetation-erosion interactions on sediment yields and landform evolution have not been adequately documented and modeled. This research will study moderate- to low-relief catchmets in central New Mexico (northwest part of the Sevilleta National Wildlife Refuge), where north-facing slopes are characterized by a juniper-grass savanna, and south-facing slopes by shrublands, with other factors such as precipitation, lithology, and elevation are relatively uniform. Existing vegetation patterns in this site are believed to have been present since the mid Holocene, before which pinon-juniper-oak woodlands dominated the region. The opposing hillslopes in the site show pervasive differences in their morphologies with north-facing slopes usually steeper and more planar than south-facing slopes, and in their ecohydrological response to monsoon precipitation. This work will investigate the co-evolution of soils, vegetation and topography using a variety of process-based research methods including ecohydrological monitoring (soil moisture, runoff, evapotranspiration, biomass); dating of surface sediments to approximate Holocene erosion rates; and numerical modeling of ecohydrology and landscape evolution. Broader Impacts: This project will train two graduate students. A project website will be jointly developed between the two institutions, reporting research results, data, and visualization of numerical model experiments. This interdisciplinary research will have a significant impact on the ongoing efforts in ecosystem monitoring studies in the Sevilleta National Wildlife Refuge. In particular, our modeling approach will offer capabilities in predicting the impacts of biome transition and land-use change on regional hydrology and sediment yields. Such modeling efforts are of critical importance in habitat conservation, restoration, and land-use planning efforts across the southwest US as well as in other semiarid regions worldwide.