The dual role of soil crusts in desertification. Issue 10 (30th October 2015)

• Record Type: Journal Article
• Authors: Assouline, S.; Thompson, S. E.; Chen, L.; Svoray, T.; Sela, S.; Katul, G. G.
• Is Part Of: Journal of geophysical research. Volume 120:Issue 10(2015:Dec.)
• Page Start: 2108
• Page End: 2119
• Publication Date: 2015-10-30
• Subjects: physical crusts -- desertification -- runoff‐runon -- recovery -- model -- infiltration; Geobiology -- Periodicals; Biogeochemistry -- Periodicals; Biotic communities -- Periodicals; Geophysics -- Periodicals; 577.14
• DOI: 10.1002/2015JG003185
• Languages: English
• ISSNs: 2169-8953

Abstract

Abstract: Vegetation cover in dry regions is a key variable in determining desertification. Soils exposed to rainfall by desertification can form physical crusts that reduce infiltration, exacerbating water stress on the remaining vegetation. Paradoxically, field studies show that crust removal is associated with plant mortality in desert systems, while artificial biological crusts can improve plant regeneration. Here it is shown how physical crusts can act as either drivers of or buffers against desertification depending on their environmental context. The behavior of crusts is first explored using a simplified theory for water movement on a uniform, partly vegetated slope subject to stationary hydrologic conditions. Numerical model runs supplemented with field data from a semiarid Long‐Term Ecological Research site are then applied to represent more realistic environmental conditions. When vegetation cover is significant, crusts can drive desertification, but this process is potentially self‐limiting. For low vegetation cover, crusts mitigate against desertification by providing water subsidy to plant communities through a runoff‐runon mechanism. Key Points: Soil crusts switch between reversing and promoting desertification Soil crusts were essential to reversal of land degradation in Lehavim LTER Results resolve divergent findings on effect of soil crusts on vegetation loss