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Desert soil surfaces are generally covered with biological soil crusts, a group of organisms dominated by cyanobacteria, lichens, and mosses. Despite their unassuming appearance, these tiny organisms are surprisingly critical to many processes in past and present desert ecosystems and are vital in creating and maintaining fertility of desert soils. They fix both carbon and nitrogen, much of which is leaked to the soils below. They stabilize soils, capture nutrient-rich dust, and can stimulate plant growth. These organisms must tolerate extreme temperatures, drought, and solar radiation, despite having relatively few wet hours for metabolic activity. Under most circumstances, they are extremely vulnerable to climate...
Desert soil surfaces are generally covered with biological soil crusts, a group of organisms dominated by cyanobacteria, lichens, and mosses. Despite their unassuming appearance, these tiny organisms are surprisingly critical to many processes in past and present desert ecosystems and are vital in creating and maintaining fertility of desert soils. They fix both carbon and nitrogen, much of which is leaked to the soils below. They stabilize soils, capture nutrient-rich dust, and can stimulate plant growth. These organisms must tolerate extreme temperatures, drought, and solar radiation, despite having relatively few wet hours for metabolic activity. Under most circumstances, they are extremely vulnerable to climate...
A portable wind tunnel was used to test the contribution of biological and physical elements to overall soil aggregation on a soil dominated by biological soil crusts in south-eastern Australia. After moderate disturbance and simulated wind erosion, 90% of surface aggregates on the loamy soil and 76% on the sandy soil were dominated by biological elements (cryptogams). Lower levels of biological bonding were observed on the severely disturbed treatment. Linear regression indicated a significant positive relationship (r2=0·72) between biological soil crust cover and dry aggregation levels greater than 0·85mm. To maintain sediment transport below an erosion control target of 5gm−1s−1 for a 65kmh−1 wind at...