Soil organic carbon(SOC) can be divided into plant and microbial-derived carbon. Studying the latitudinal variation of these two sources and its controlling factors is vital to understand SOC persistence and stabilization.

To analyze the variation of plant and microbial derived carbon in topsoil and subsoil along different latitude gradients, the Global Change Ecology Group of Wuhan Botanical Garden selected six typical forests, ranging from Jianfengling to Genhe along a latitude gradient as study sites. Amino sugars and lignin phenols were used as biomarkers to indicate microbial- and plant-derived carbon, respectively. The study comprehensively analyzed the effects of climate, vegetation, soil, and microbial properties on the concentration changes of lignin phenols and microbial residues in topsoil and subsoil along the latitude gradient.

The study finds that the amino sugar and lignin phenol contribute as much as 50%-75% of the SOC, and their contributions decrease with latitude. The contributions of the former increase with soil depth, whereas the latter are the opposite. Climate and soil physicochemical properties mainly control the persistence of microbial residues and lignin phenols in topsoil, and soil clay is the crucial factor in determining the microbial residues and lignin phenols in the subsoil.

These results have guiding significance for understanding the contribution and accumulation mechanism of organic carbon from lignin phenols and microbial residues in forest soils, and are helpful for predicting the carbon sink potential of forest ecosystems under future global climate change.

This work was supported by the Natural Science Foundation of China, which has been published in Journal of Soils and Sediments entitled “Persistence of soil microbial residuals and lignin phenols in forest ecosystems along the latitude gradient”.

The variation of amino sugars and lignin phenol concentrations along the latitude gradient in topsoil and subsoil (Image by WBG)