Biological soil crusts (BSCs) result from the close association between soil particles and various microorganisms, including cyanobacteria, green microalgae, and free- living fungi. In this study, we investigated the BSC microflora in soil samples collected from four sites in Qom Province, a semi-arid region in Iran. The study stations included agricultural areas, farms irrigated with saline water, and the edge of Hoz-e-Soltan Lake, a saline water lake. To study algal communities, all soil samples were cultivated in four different culture media including BG11, BG11 with 1.5 M NaCl, nitrate-free BG11 medium (BG110), and BG110 with 1.5 M NaCl. We isolated and identified 37 morphospecies of algae. Cyanobacteria, such as Phormidium and Pseudanabaena, were dominant genera at most stations. Additionally, green algae and diatoms were present in the studied sites. Our results revealed that algal diversity in BSCs depends on soil physio- chemical characteristics of the soil. For example, Phormidium was the dominant genus in all agricultural soils, while in saline soils, the genus Dunaliella was reported as the dominant taxon. Therefore, salinity plays a crucial role in shaping species distribution and diversity in these ecosystems.