The CAZyme family regulates the changes in soil organic carbon composition during vegetation restoration in the Mu Us desert

• Typical grassland and artificial forest soils contain a higher proportion of recalcitrant carbon. • Lignin and peptidoglycan degradation functions are stronger in typical grassland and artificial forest soils. • Microorganisms in grassland deserts and desert steppes prefer labile carbon. • Methyl carbon is the most active in the decomposition of organic matter. Combatting desertification through vegetation restoration holds significant potential for soil carbon sequestration. However, understanding the effects of different restoration types on soil organic carbon component and the role of carbohydrate-active enzymes (CAZymes) remains limited. This study assessed soils from four distinct vegetation types, namely grassland desert (GD), desert steppe (DS), typical steppe (TS), and artificial forest (AF), in the eastern part of the Mu Us Desert, China, examining physicochemical properties, carbon chemical composition, microbial community composition, and CAZyme gene abundance. Our research findings demonstrated that TS restoration significantly increased the content of various soil organic carbon (SOC) components. Compared to other vegetation types, the proportion of recalcitrant carbon (20–22%) was notably higher and exhibited a strong correlation with lignin and peptidoglycan, as determined by the analysis of CAZyme subfamily composition. GD and DS soils showed enrichment in cellulose and hemicellulose-decomposing CAZymes, leading to higher polysaccharide and aliphatic carbon levels. Significant changes were observed in the methyl carbon component amidst the decomposition of varied organic matter types, correlating strongly with Proteobacteria and Acidobacteria abundances. Our research elucidates the influence of distinct vegetation types on sandy soil carbon sequestration and stabilization, highlighting the crucial function of microbial communities and their CAZyme activities. These insights can guide enhanced land management strategies for improved carbon dynamics in arid ecosystems.