Response of soil basal respiration rates, microbial attributes, and organic matter composition to land-use change

Abstract

Land-use change directly impacts soil basal respiration (Br), soil microbial attributes, and soil organic matter (SOM) composition. However, the role of soil microbial attributes and SOM composition in influencing soil Br under land-use changes remains largely undetermined. We examined how interactions between soil physicochemical properties, SOM chemical structure, and microbial attributes regulate soil Br across three land-use types, cropland, forest, and grassland, in the Mollisol and Arenosol of Horqin Sandy Land. The results showed that soil Br, phospholipid fatty acid content, and the relative peak areas of aliphatic and aromatic compounds were significantly lower in cropland than in forest and grassland. Additionally, the Arenosol exhibited poorer soil properties compared to the Mollisol (p < 0.05). Soil Br in the Mollisol (3.60–5.56 mgCO₂-C kg⁻¹ h⁻¹) was significantly higher than in the Arenosol (0.86–2.60 mgCO₂-C kg⁻¹ h⁻¹, p < 0.05). G⁺/G⁻ ratios and bacteria were identified as the main predictors of Br in the Mollisol and Arenosol, respectively. The structural equation model revealed that microbial attributes are the primary drivers of Br, influencing it indirectly through changes in SOM composition. Our findings are instrumental in understanding the role of microbial attributes in carbon turnover during land-use changes.