Vegetation Organization in a Semiarid Ecosystem in Central New Mexico
Semiarid and desert ecosystems are characterized by patchy and dynamic vegetation. Topography plays a commanding role on vegetation patterns. Plant biomes and biodiversity vary systematically with slope and aspect, from shrublands in low desert elevations, to mixed grass/shrublands in mid elevations, and forests at high elevations. We investigate the role of elevation dependent climatology and aspect on vegetation organization in semiarid catchments where elevation and hillslope aspect play a defining role on plant types. We use observational and satellite-based and numerical modeling using Landlab. We developed the Cellular Automaton Tree Grass Simulator CATGraSS [Zhou et al., 2013], an ecohydrologic cellular automaton model, now implemented in Landlab. The model couples local vegetation dynamics (that simulate biomass production based on local soil moisture and evapotranspiration) and plant establishment and mortality based on competition for resources and space. This model is driven by elevation dependent rainfall pulses and solar radiation. An example of CATGraSS model application in Landlab is presented in the figure below: (a) CATGraSS model flow chart showing flow between different model components; (b) time series of modeled grass, shrub, and tree cover fractions for CATGraSS implementation on a flat domain for central New Mexico climatology. Spatial distributions of plants in model initial condition (c), after 1,000 years (d), and year 1,500. Model shows epochs of shrub and grass dominance in the modeled domain, while trees were outcompeted.
Semiarid and desert ecosystems are characterized by patchy and dynamic vegetation. Topography plays a commanding role on vegetation patterns. Plant biomes and biodiversity vary systematically with slope and aspect, from shrublands in low desert elevations, to mixed grass/shrublands in mid elevations, and forests at high elevations. We investigate the role of elevation dependent climatology and aspect on vegetation organization in semiarid catchments where elevation and hillslope aspect play a defining role on plant types. We use observational and satellite-based and numerical modeling using Landlab. We developed the Cellular Automaton Tree Grass Simulator CATGraSS [Zhou et al., 2013], an ecohydrologic cellular automaton model, now implemented in Landlab. The model couples local vegetation dynamics (that simulate biomass production based on local soil moisture and evapotranspiration) and plant establishment and mortality based on competition for resources and space. This model is driven by elevation dependent rainfall pulses and solar radiation. An example of CATGraSS model application in Landlab is presented in the figure below: (a) CATGraSS model flow chart showing flow between different model components; (b) time series of modeled grass, shrub, and tree cover fractions for CATGraSS implementation on a flat domain for central New Mexico climatology. Spatial distributions of plants in model initial condition (c), after 1,000 years (d), and year 1,500. Model shows epochs of shrub and grass dominance in the modeled domain, while trees were outcompeted.
Reference: Hobley, D. E., Adams, J. M., Nudurupati, S. S., Hutton, E. W., Gasparini, N. M., Istanbulluoglu, E., & Tucker, G. E. (2017). Creative computing with Landlab: an open-source toolkit for building, coupling, and exploring two-dimensional numerical models of Earth-surface dynamics. Earth Surface Dynamics, 5(1), 21.