Influence of biocrust islands on organic carbon changes along the soil profile in Sejzi Plain, Iran

Context Organic carbon (OC) plays a vital role in regulating ecological processes and biogeochemical cycling within soil ecosystems. However, there is a lack of information regarding OC concentrations and stoichiometric ratios at different soil depths, particularly in the biocrusted soils of Iran’s dryland regions. Aims To address this knowledge gap, this study aimed to assess the carbohydrate and OC content produced by biocrusts in the Sejzi Plain, located in Isfahan Province, Iran. Methods Using a stratified random method, soil samples were collected from three distinct sites. Soil parameters were analyzed across three horizons: A (0–5 cm), Btk (5–35 cm), and Byk (35–55 cm). Fourier transform infrared spectroscopy was employed to identify soil compounds and compare them between areas with and without biocrust cover. Key results Two-way ANOVA results showed that OC, carbohydrates, and mean weight diameter (MWD) were affected by biocrusts throughout the soil profile. Also, a multivariate linear regression model using a stepwise method revealed that in the A horizon, OC, carbohydrates, sand, silt, clay, and MWD were significant variables. In the Btk horizon, carbon, carbohydrates, and MWD were identified as important factors; in the Byk horizon, only OC was significant. Conclusions The biocrusts had a substantial impact on the soils, leading to the exclusion of other parameters from the model. This suggests that the biocrusts contributed to an increase in OC and carbohydrates within the soil profile of 0–35 cm depth. Implications These results provide valuable insights for ecosystem restoration initiatives.