Independent response of soil DOM to MAT and MAP: Evidence from a large-scale survey of moss crusts in mainland China

Abstract

It is known soil dissolved organic matter (DOM) plays an important role in global biogeochemical cycle and is an important factor in soil-forming processes. However, the linkage between the diversity of chemical composition and properties of DOM molecules and the climatic conditions (temperature, precipitation) at regional scales is still not well studied. Therefore, in our study, we selected 33 soil DOM samples which were, divided into temperature-variation and precipitation-variation groups, and used Fourier transform ion cyclotron resonance mass spectrometry to analyze the influence of climate on the chemical characterizations of DOM. Our results showed that although the factors affecting the chemical properties of DOM are complex, mean annual precipitation (MAP) and mean annual temperature (MAT) can explain part of the chemical changes of DOM, and the two data sets in this study can well separate the effects of MAP and MAT on DOM, respectively. The results showed that the content of lignin and tannin were positively related to MAP, while carbohydrate, lipid, unsaturated hydrocarbon and protein decreased with the increase in MAP. The content of nitrogen-containing molecules gradually decreased with the increase in MAT. Meanwhile, the content of sulfur-containing molecules was almost unaffected by the MAP and MAT. In terms of DOM composition, the content of protein decreased with the increase in MAT. The results suggested that the chemical characteristics of DOM is an ecosystem attribute that is closely related to the environment and may be used to predict large-scale soil biochemical processes in the soil carbon cycle.

Keywords

• Climatic factors
• Dissolved organic matter
• Chemical characteristics