DDD Conference

Dr. Eli Zaady

Restoration of Cyanobacterial Crust as an Interface in the Critical Zone for Stabilizing Sandy Soil Surface

Volcani Institute, Agricultural Research Organization, Israel

The biocrusts are critical factors in landscape structure and function. In dryland environments, where water is the main limiting factor, biocrusts are considered ecosystem engineers and play significant roles in ecosystem processes. Metabolic polysaccharides secreted by cyanobacteria glue the soil particles to aggregates, which form the crust layer, allowing better water retention in the soil over time by reducing evaporation and desiccation and stabilizing the soil surface.

 

Cyanobacterial crusts play a crucial role in geomorphological processes by preventing wind erosion. There is positive feedback between the biocrusts and the percent of fine particles in the soil surface layer. The lack of clay and silt inhibits cyanobacterial crust colonization growth rate, even in relatively wet desert areas with 100–250mm average annual rainfalls. The incorporation of dust particles into biocrusts increases the growth of cyanobacteria, strengthening the biocrusts’ cohesion.

The expansion of agriculture into drylands leads to the use of fragile sandy soils that are potentially inappropriate for farming. Sand transport systems can change significantly in short periods. Therefore, active dunes pose one of the main problems in desertified lands, as in vast areas worldwide, and stabilizing dunes after disturbance is a significant challenge. Restoring disturbed dunes by enriching their surface with silt and clay particles will enhance cyanobacterial colonization and dune stabilization, reducing the sand transport damage in the farmland.

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