Factors Controlling Microbiotic Crusts: Negev and New Mexico
Investigators (most current known information)
The main goals of the current project were to monitor the water regime of microbiotic crusts at different desert terrains, to understand the mechanisms that allow the surface crusts to be active for hundreds of hour a year, and to understand the crust role in water and nutrient redistribution in the Chihuahuan and Negev deserts.
Owing to the small and sporadic nature of precipitation in the desert and the high surface temperatures, one would expect the upper centimeter of the surface to dry up soon after rain. Yet, our measurements have shown that the surface may remain wet, at least for some hours during the day and up to two weeks following a rain spell. During the current research, detailed measurements have shown that high temperature gradients within the upper soil surface results in moisture fluctuation, apparent also to the naked eye as wet-dry cycles. These cycles were monitored with specially designed gypsum blocks. Our measurements have concluded that dew does not play any important role in the water budget of cyanobacterial crusts and that water vapor condensation is restricted to cold nights and therefore to the winter period. Measurements of runoff in the Jornada (Chihuahua), White Sands (Chihuahua) and Nizzana (Negev) research sites have pointed out to the complex role of crusts in water redistribution. Whereas no runoff was monitored in the White Sands regardless of crust presence, microbiotic crusts impeded runoff on loess in the Jornada. In Nizzana, however, microbiotic crusts promoted runoff. Furthermore, the crust had an important role in nutrient redistribution, thus enriching the dense belt of shrubs in the dune-interdune interface, runoff may also explain crust and grass patchiness in the Jornada. There, both crusts and grasses may serve as biological indicators for soil moisture regime.
Articles in Journals
Kidron, G.J., Vonshak, A. and A. Abeliovich. 2009. Microbiotic crusts as biomarkers for surface stability and wetness duration in the Negev Desert. Earth Surf. Process. Landforms 34: 1594–1604. Published online 28 July 2009 in Wiley InterScience (www.interscience.wiley.com) DOI: 10.1002/esp.1843.
Kidron, G.J. 2009. The effect of shrub canopy upon surface temperatures and evaporation in the Negev Desert. Earth Surf. Process. Landforms 34: 123–132. Published online 5 August 2008 in Wiley InterScience (www.interscience.wiley.com) DOI: 10.1002/esp.1706.
Kidron, G.J., Vonshak, A. and A. Abeliovich. 2008. Recovery rates of microbiotic crusts within a dune ecosystem in the Negev Desert. Geomorphology 100: 444-452. Published online 2 February 2008 in ScienceDirect (www.sciencedirect.com). DOI: 10.1016/j.geomorph.2008.01.012.
Kidron G.J. and Monger, H.C. 2001. "The impact of microbiotic crusts upon runoff in three parent materials in the Negev and the Chihuahuan Deserts geomorphological, climatological and paleo-climatological implications." Presented, Israel Geological Society annual meeting, 70. March. Eilat, Israel.
Kidron G.J. and Monger, H.C. 1999. "Microbiotic crusts as indicators of surface moisture and erosion." Presented, Soil Science Society of America annual meeting, 234. October - November. Salt Lake City UT.
Kidron G.J. and Monger, H.C. 1999. "Assessing environmental conditions using microbiotic crusts." Presented, International conference on drainage basin dynamics and morphology, May. Jerusalem, Israel.