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.

植物通过凋落物和根向土壤食物网提供碳（C）输入到土壤和能源资源。然而，仍然不确定哪个碳输入途径更重要，以及不同的碳输入如何影响土壤动物群落组成。进行了长期（9年）野外碳输入操纵实验，以研究碳输入对土壤线虫的影响。进行了除草，添加凋落物和清除凋落物的模拟，以模拟地下和地下C输入的变化。结果表明，去除植物会显着降低土壤资源的利用率（即土壤有机碳和总氮）。去除植物还降低了线虫的丰度（73.09％）和属丰富度（17.98％）。通过去除植物，可提高细菌的相对丰度，但减少了植物寄生虫和杂食性捕食者的数量。在植物去除处理下的₃ ^-- N浓度可能是导致群落结构改变的原因。凋落物的添加使线虫的丰度提高了37.88％，但清除凋落物的种类使线虫的丰富度降低了9.39％。去除植物和凋落物处理对线虫总丰度和属丰富度有显着的交互作用。我们的观察表明，地下碳输入对土壤线虫的影响要大于地上碳输入，并且凋落物对土壤线虫群落的影响可能是由有生命的植物介导的。