Ants alter molecular characteristics of soil organic carbon determined by pyrolysis-chromatography/mass spectrometry

Colonization by ecosystem engineers, such as ants, have important but occasionally unnoticed roles in regulating soil carbon cycles. However, little information is available pertaining to ant effects on changing molecular features of soil organic matter. In this study, we characterized total soil organic carbon (SOC), total nitrogen, water extractable organic carbon (WEOC) as well as molecular characteristics of humic acids (HAs) of ant mound soils (SoilAnt) and the surrounding soils (SoilCon) using pyrolysis-chromatography/mass (py-GC/MS). SOC, total nitrogen and WEOC contents of SoilAnt were significantly lower than those of SoilCon. SoilAnt samples had significant higher nitrogen containing compounds proportions in pyrolysis products of HAs as opposed to SoilCon samples. Another remarkable characteristic was that no polysaccharides, lignin, and phenols were identified in HAs of SoilAnt samples. It indicated that ant colonization significantly changed the molecular composition of soil organic matter.