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Biological Soil Crusts (BSC) are important ecological constituents found in a wide range of environments. In arid environments, they are particularly important as they provide structure to the soils and allow vascular plant communities to become established and develop. The terrestrial BSC coverage for the state of Qatar was documented by measuring the crust coverage in 33 x 1 m(2) quadrats in each of 91km(2) blocks, accounting for 80% of the country. The coverage of BSC, comprised mainly of cyanobarteria, was found to vary within blocks and between blocks, with mean percentage coverage ranging between 0 and 87%. A north east (greatest) to south west (least) gradient was observed, corresponding with changes in soil type and topographical features. Assessing the coverage of BSC across the State of Qatar will be a useful baseline to monitor environmental disturbance and protect the loss of valuable soils in this arid environment. (C) 2011 Elsevier Ltd. All rights reserved.