Accumulation of microbial residuals and lignin phenols in forest soils along the latitude

Abstract Aims The carbon inputs from plant and microbial sources mainly govern the storage of soil organic carbon (SOC). However, how their relative contributions to SOC may vary along broad-scale environmental gradients is still poorly understood; the vertical distribution of these two carbon sources in soils is also elusive. Methods We selected amino sugar (microbial-derived carbon) and lignin phenol (plant-derived carbon) as biomarkers. The accumulation of amino sugar and lignin phenol in topsoil (0-10cm) and subsoil (30-50cm) of major forest types along latitude gradients in China was quantified. Results Our result showed that amino sugar concentrations decreased along latitude in topsoil. This was mainly influenced by annual mean temperature (MAT) and soil nitrogen (N). Lignin phenol concentrations decreased along latitude in topsoil, mainly influenced by soil C/N ratio. The soil amino sugar concentrations in topsoil were lower than those in subsoil, and the opposite was true for lignin phenols. In topsoil, the microbial-derived carbon was mainly composed of fungi-derived carbon, while in subsoil, bacteria-derived carbon dominated. Conclusions The microbial residues were mainly influenced by climate and soil properties. The lignin phenols were mainly controlled by soil properties. The controlling factors for microbial residues and lignin phenols in topsoil and subsoil are different. Our works have established a connection among climate, vegetation, and soil, revealing significant mechanisms for the vertical distribution of carbon sequestration along a latitude gradient.