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Mojave Desert Soils

Mojave Desert Soils. And Associated Plant Life. With Case Studies of the Mojave River Floodplain, Larrea and Ambrosia Species Preference, And Succession in the Panamint Mountains . suif.stanford.edu/~nickolai/photos. Overview. General constraints of soil

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Mojave Desert Soils

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  1. Mojave Desert Soils And Associated Plant Life With Case Studies of the Mojave River Floodplain, Larrea and Ambrosia Species Preference, And Succession in the Panamint Mountains. suif.stanford.edu/~nickolai/photos

  2. Overview • General constraints of soil • Geologic setting for Mojave river soils • Differential plant use of soil horizons • Plant Succession on Panamint Mountains suif.stanford.edu/~nickolai/photos

  3. So what’s the big deal? Well… water. Poor infiltration into desert pavement → clay Low water table, quick evaporation Salts, toxins → ex: black alkali Diagram Curtesy of Arvidson, adapted from Strahler (1963). 

  4. Black Alkali • sodium clays ----hydrolyzes----> sodium hydroxide ---CO2---> sodium carbonate(high pH) (soil air) • sodium carbonate ---organic matter---> black crust on surface - 'black-alkali • Sodium Dispersal and soil swelling • In competition with clay Swelling by exchangable sodium percentage Picture by Allan Grogan /www.agric.nsw.gov.au/Agedu/Tocal/salinity Chart: waterquality.montana.edu/docs(After McNeal, 1968).

  5. Organic Matter Flowering Acacia • Typically, not there: Need for Nitrogen Sources: Bacteria, Algae, Legumes http://mgordonphotography.com/images/gallery2006/031_lg.jpg http://www.pbase.com/bearpaw/image/28377252

  6. Alluvial fans and braided stream deposits: sand, unconsolidated gravel Subsurface silt and clay Calcerous playa sediments Igneous and metamorphic ridges Geologic Setting:minerals and spacing of substrate

  7. Larrea Tridentata “During Peak Spring conditions, pre-dawn water potential and midday net photosynthetic assimilation were highest in Larrea at the intermediate alluvial site where soils had substantial surface and subsurface horizons, and at the pavement site where soils had strong surface layers but little susurface development” Ambrosia Dumosa “In contrast to Larrea, density of Ambrosia increased with soil horizon development, but smaller plant sizes resulted in similar canopy volume per area and identical pre-dawn water potential and midday net photosynthetic assimilation across all soils where it occurred, suggesting greater plasticity to the transmittal of precipitation.”

  8. www.nazflora.org/Larrea

  9. Larrea and its substrate Lack of clay rich B layer, thinner soils. Larrea Canopy height and basal diameter greatest on young alluvial fan Post-storm plant activity greatest at young alluvial fan Plant density greatest at intermediate alluvial fan.

  10. Soil composition as important as overall precipitation. Difference: development of thick A and B soil horizons. How much water, where is the water going, how long does it stay there?

  11. Young Alluvium and Dunes Intermediate Alluvium Older Alluvium and Pavement Larrea Summary www.nazflora.org/Larrea

  12. Succession through three stages: • Youngest debris flow characterized by twelve species not present at the other two sites. Most abundant plant Lupinus Excubitus. • Intermediate debris flow contained a significant number of coleogyne and lycium. Grayia dominant in small local pockets. • Oldest debris flow at this and other sites maintained a large percentage of coleogyne plants. Ambrosia Lupinus Grayia Coleogyne www.kenbowles.net/SDwildflowers/ biology.burke.washington.edu/herbarium/

  13. Sources Pearson, Krista E. “The Basics of Salinity and Sodicity Effects on Soil Physical Properties”. Adapted by Krista E. Pearson from a paper by Nikos J. Warrence, Krista E. Pearson, and James W. Bauder (2003). waterquality.montana.edu/docs/methane/basics_highlight.shtml. Fuller, Wallace H. Soils of the Desert Southwest. Tucson : University of Arizona Press, 1975. Stamos, Christina L. et al. “Geologic setting, geohydrology and ground-water quality near the Helendale Fault in the Mojave River basin, San Bernardino County, California.” Sacramento, Calif. : U.S. Dept. of the Interior, U.S. Geological Survey. 2003. Hamerlinck, Eric P. et al. Ecological Responses of Two Desert Shrubs to Soil Horizon Development and Soil Water Dynamics. Ecology, 83(3). pp 768-779. 2002. Webb, Robert H., Steiger, Turner. “Dynamics of Mojave Desert Shrub Assemblages in the Panamint Mountains, California.” Ecology, 68(3). Pp 478-490. 1987.

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