Loss of plant functional groups impacts soil carbon flow by changing multitrophic interactions within soil micro-food webs

The ecological linkage between above- and belowground parts of the terrestrial ecosystem is of interest to ecological and management fields. However, the knowledge on how the loss of plant functional groups impacts multitrophic interactions across soil biota and associated ecological functioning knowledge is lacking. This study aimed to evaluate responses of soil nematode communities to PFG (Gramineae, Cyperaceae, Leguminosae, and other Forbs) identity and richness loss after 9 years by comparing 15 treatments. Specifically, the loss of PFG richness significantly decreased carbon biomass and the abundance of bacterivores and negatively affected footprints of bacterivores and omnivore-predators (OP), leading to a decline in the enrichment and structure footprints. The response of nematode community structure and functional composition at different trophic levels to PFG richness loss varied with PFG identity. Gramineae removal reduced the community structural footprint positively associated with the biomass carbon and footprint of OP, suggesting carbon and energy enrichment are likely to be lower in soil micro-food webs. Although the removal of Cyperaceae reduced carbon biomass and the footprint of bacterivores, it did not cause significant shifts in carbon and energy enrichment and structural footprints in the soil food web, similar to the other two PFGs. Notably, Gramineae strongly controlled carbon and energy enrichment regulations in soil micro-food webs than other PFGs. The present study highlights the key role and influence of PFG richness and identification on food web ecosystem services. It provides a basis for the development of sustainable strategies for grazed alpine meadow ecosystem's management.