Effect of biological soil crusts on soil chemical properties: a study from Tunisian arid ecosystem

Abstract Biological soil crusts (BSCs) composed of cyanobacteria, green algae, bryophytes, and lichens are a major biotic component of arid and semi-arid rangeland environments worldwide. They are recognized and studied in many parts of the world. However, they have been the subject of very few studies in Africa. The current study deals with the assessment of the influence of BSCs on soil chemistry in an arid ecosystem in Southern Tunisia. Our main objective is to test whether biological soil crusts are able to improve soil chemical properties. Our investigation showed that biological soils crusts had an expressive effect on soil chemistry. In fact, biologically crusted soils had higher levels of pH, electrical conductivity, organic matter, organic carbon, nitrogen, phosphorus, Ca, K, Na, Cl and lower C: N ratio compared to biologically un-crusted soils. The differences between crusted and un-crusted soils were statistically significant at 95% confidence. The PCA results demonstrate further that BSCs significantly enhance soil surface properties. These data support other studies revealing an improvement of the soil chemical properties by means of biological soil crusts.