Elevation Control on Vegetation Organization in a Semiarid Ecosystem in Central New Mexico Sai Siddhartha Nudurupati1, Erkan Istanbulluoglu1, Jordan M. Adams2, Daniel Hobley3, Nicole M. Gasparini2, Gregory E. Tucker3 and Eric W. H. Hutton4 1 Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, USA 2 Department of Earth and Environmental Sciences, Tulane University, New Orleans, LA, USA 3 CIRES and Department of Geological Sciences, University of Colorado, Boulder, CO, USA 4 Community Surface Dynamics Modeling System (CSDMS), University of Colorado, CO, USA INTRODUCTION Semiarid and desert ecosystems are characterized by patchy and dynamic vegetation Topography has been observed to play a commanding role on vegetation patterns In this study, we investigate the role of elevation dependent climatology on vegetation organization in a semiarid catchment in New Mexico, USA We develop a ecohydrologic cellular automaton model within Landlab, a component based modeling framework for earth surface (http://landlab.readthedocs.org). The model couples local vegetation dynamics model with cellular automata plant establishment and mortality model based on Zhou et al. (2013). The model is driven by elevation dependent rainfall, temperature and radiation Model results reproduce elevation and aspect controls on observed vegetation patterns LANDLAB: ECOHYDROLOGY VEGETATION ORGANIZATION: ASPECT VEGETATION ORGANIZATION: ELEVATION MODELING ELEVATION DEPENDENCEKnow More About The Landlab here: http://Landlab.github.ioContact: saisiddu@uw.edu & erkani@u.washington.edu Landlab Ecohydrology Components: Storm Generator: generates rectangular Poisson distributed storms Radiation: calculates daily spatially distributed solar radiation (Radiation Factor) Potential Evapotranspiration (PET): uses solar radiation fields and weather variables to calculate PET at each model element Soil Moisture: solves root zone water balance between two storms given PET and rainfall fields ; returns actual evapotranspiration and soil moisture at inter storm durations Vegetation: computes net primary productivity based on actual evapotranspiration and calculates leaf area index and biomass Cellular Automata Competition: models competition by keeping track of probabilistically calculated mortality and establishment of plants driven by water stress and plant age Fig. 1: Point Model Validation of Leaf Area Index at Nebraska Sand Hills Fig. 2: Simulation on flat topography Fig. 3: Simulation on actual topography in Sevilleta, Central New Mexico Fig. 5: Observed elevation dependent land cover in a catchment in central New Mexico Fig. 4: Elevation dependence on Potential Evapotranspiration and Precipitation [1]References: 1. Caylor, Kelly K., Salvatore Manfreda, and Ignacio Rodriguez-Iturbe. "On the coupled geomorphological and ecohydrologicalorganization of river basins." Advances in Water Resources 28.1 (2005): 69-86.2. Zhou, Xiaochi, Erkan Istanbulluoglu, and Enrique R. Vivoni. "Modeling the ecohydrologicalrole of aspect‐controlled radiation on tree‐grass‐shrub coexistence in a semiarid climate." Water Resources Research 49, no. 5 (2013): 2872-2895. CONCLUSIONS To increase computational efficiency ecohydro- logically similar grids are developed into bins for soil moisture and water stress simulations. 10 slope bins X 12 aspect bins X 5 elevation bins X 4 vegetation type bins are used. Water stress is mapped from representative grid to actual (topography) grid annually. CA plant competition is driven by water stress Sample Area for Analysis PET & Precip Gradient: Year 2000 Precip Gradient: Year 2000 PET Gradient: Year 2000 Landlab Driver for this Analysis Fig. 6: Modeled elevation dependent vegetation organization in a catchment in central New Mexico This study demonstrates a preliminary evaluation of Landlab: Ecohydrology in Central New Mexico. The model shows general agreement with observed aspect-dependent and elevation-dependent