The effect of different sequences of biological crusts on soil physicochemical properties in dry land

Biological crusts are a collection of mosses, lichens, algae, fungi and heterotrophic bacteria that live in different forms within a few millimeters above the soil surface. These crusts play an important role in the development, stability and improvement of the nutritional status of the surface soil. Therefore, this study was conducted to investigate the role of biocrust sequences on the soil characteristics in the Inche Barun region, Golestan province (Iran). In the study area, biological and physical crusts as well as the soil under their surface were sampled after identifying the sequences of biocrust (moss, lichen and cyanobacteria). Then, the physicochemical characteristics of soil under their surface (In the depths 0-2, 2-4, 4-8, 8-10, 10-25, and 25-50 cm) were measured. The results showed that the presence of biological crusts compared to physical crust in the surface parts (0 to 2 cm depth) improved the physicochemical properties of the soil. The content of nitrogen, soil organic carbon, phosphorus, cation exchange capacity, sodium, potassium and mean-weight diameter of soil in the soil under their surface increased from the first (physical crust) to the last sequence (moss biological crust). The values of these parameters decreased with increasing soil depth. Biological crusts improve soil stability and reduce soil erosion. They also serve as food sources for organisms residing in soils. Therefore, it can be concluded that the presence of biological crusts on the soil surface improves soil quality.