Soil Macrofauna Diversity and Carbon Storage in the River-Lake Confluence Area of Hung-tse Lake: Responses to Human-Induced Land Use (Vegetation) Changes

Aims Soil macrofauna play crucial roles in biogeochemical processes, energy flow, and material cycling. However, the carbon storage in soil macrofauna residues, including its distribution characteristics and influencing factors, remains poorly understood. This study aims to (1) enhance the understanding of how human-induced changes in wetland land use（vegetation）affect the diversity and carbon storage of soil macrofauna; (2) investigate the main factors influencing their carbon storage in the River-Lake confluence area of Hung-tse Lake. Methods Soil macrofauna were collected from natural and human-impacted land use (vegetation) types in the River-Lake confluence area of Hung-tse Lake in eastern China, and the carbon storage of soil macrofauna under different land use (vegetation) types was measured. Results Our study found that the soil macrofauna residue carbon storage (every 20 cm depth) was highest in the poplar cover (1.42 g C/m2), followed by the willow cover (0.91 g C/m2), while lake meadows and reed beds exhibited lower values. Structural equation modeling revealed that the direct factors influencing the soil macrofauna carbon storage were the relative abundance of soil macrofauna, soil microbial biomass carbon areal density, soil fungal richness index, soil electric conductivity and soil pH. Conclusions Our results demonstrate that land use (vegetation) type significantly impacts the soil macrofauna residue carbon storage in the River-Lake confluence area of Hung-tse Lake. Furthermore, soil macrofauna residue carbon can be quantified as an independent carbon pool within the entire wetland ecosystem.