Investigating soil trophic links in a peatland, northeast China: Dual stable isotope analysis (δ13C and δ15N) of microarthropods and their food sources

Peatlands are crucial global carbon sinks and key players in carbon cycles, with their soil food webs supporting vital ecosystem processes. However, trophic relationships and carbon source uses of soil microarthropods in peatlands are poorly understood, limiting our understanding of their role in material cycling and ecosystem stability. Here, we employed dual stable isotope analysis (δ¹³C and δ¹⁵N) to investigate the trophic structure and carbon source utilization of soil microarthropods (Collembola, Oribatida, and Mesostigmata) in the Hani Peatland of northeastern China. Our results reveal clear trophic differentiation among taxa, with Mesostigmata occupying higher positions and Oribatida displaying broader isotopic niches. Although Collembola exhibited a weak correlation between body mass and isotope values, this pattern was not consistent across taxa. Mosses, particularly Polytrichum strictum, contributed significantly to the carbon intake of Collembola and Oribatida. However, δ¹³C enrichment patterns suggest that carbon transfer is primarily mediated through moss-associated microbial pathways rather than direct moss consumption. These findings provide novel insights into the structure and functioning of peatland soil food webs and highlight the ecological importance of microarthropods in belowground biogeochemical cycling. Understanding their roles is critical for predicting peatland responses to environmental change and informing conservation strategies.