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What stabilizes biological soil crusts in the Negev Desert?

Felde, Vincent John Martin Noah Linus, Chamizo, Sonia, Felix-Henningsen, Peter, Drahorad, Sylvie Laureen
Plant and soil 2018 v.429 no.1-2 pp. 9-18
arid lands, biological soil crusts, carbonates, clay, desertification, livestock, organic carbon, plant growth, resistance to penetration, sandy soils, silt, soil electrical conductivity, soil stabilization, structural equation modeling, topsoil, trampling damage, water shortages
AIMS: Biological soil crusts (biocrusts) are widespread in many drylands, where plant growth is limited due to water scarcity. One of their most important functions is the stabilization of the topsoil, particularly in regions with sandy soils prone to desertification. Since the mechanisms playing a role in soil stabilization are poorly understood, this study aims to shed light on the connection between crust stability and different cementing agents. METHODS: We measured the penetration resistance and the concentrations of different cementing agents of biocrusts in the Israeli Negev Desert. Structural equation modelling was performed to examine the direct and indirect effects of the variables analyzed and identify variables that are best able to explain the observed patterns of penetration resistance. RESULTS: All observed variables showed a high variability within and between sites. Structural equation modelling revealed that the main parameters explaining penetration resistance are the content of fines and the electrical conductivity, while carbonates and organic carbon only have an indirect effect. CONCLUSIONS: Our results suggest that adding silt and clay to (natural or induced) biocrusts is very likely to produce stronger, more stable crusts, which will be more effective in combating desertification and improve their ability to survive trampling by livestock.