Effects of different carbon inputs on soil nematode abundance and community composition

Abstract

Plants provide carbon (C) input to the soil and energy resources for soil food webs through litter and roots. However, it remains uncertain which C input pathway is more important and how different C inputs affect the community composition of the soil fauna. A long-term (9 years) field C input manipulation experiment was conducted to investigate the effects of C inputs on soil nematodes. Plant removal, litter addition, and litter removal were carried out to simulate changes in below- and aboveground C inputs. Results showed that plant removal significantly decreased soil resource availability (i.e., the soil organic C and total nitrogen). Plant removal also decreased nematode abundance (73.09%) and genus richness (17.98%). The relative abundance of bacterivores was enhanced but plant parasites and omnivores-predators were reduced by plant removal. The significantly lower soil pH and higher NO3−-N concentrations under the plant removal treatment are probably responsible for changing the community structure. Litter addition increased nematode abundance by 37.88%, but litter removal decreased the genus richness by 9.39%. There were significant interactive effects of plant removal and litter manipulation on the total nematode abundance and genus richness. Our observations suggest that belowground C input has greater impacts on soil nematodes than the above-ground C input, and that the impacts of litter on the soil nematode community could be mediated by living plants.