乔木根系和凋落物对南亚热带3种人工林土壤线虫群落的差异化影响

根系分泌物和凋落物为土壤食物网提供了基础的养分资源。然而，不同树种纯林和混交林地下根系和地上凋落物对土壤线虫群落的影响机制尚不清楚。2019年9月在广西凭祥热带林业实验中心选取格木(Erythrophleum fordii Oliv.)纯林、马尾松(Pinus massoniana Lamb.)纯林和格木×马尾松混交林3种林分类型，分别设置对照、阻断乔木根系、去除地上凋落物和阻断乔木根系并去除地上凋落物四组实验处理，于2021年3月对3种林分类型不同处理下的土壤线虫群落和土壤理化性质进行了调查。研究结果表明，无论哪种林分类型，阻断根系改变了土壤线虫群落的营养类群组成，显著降低了食真菌线虫相对多度，增加了植物寄生线虫相对多度；去除凋落物显著降低了土壤线虫密度、类群数、线虫通路比值和结构指数，增加了基础指数，表明去除凋落物降低了土壤食物网的稳定性。无论哪种林分类型，人工林中树木地下根系输入是构建土壤线虫群落营养类群组成的主要驱动因素，地上凋落物在维持土壤食物网稳定性方面发挥着重要的作用。此外，阻断根系和去除凋落物对混交林中土壤线虫群落没有显著的影响，表明含固氮树种的格木×马尾松混交林比人工...

Differential impacts of tree root and litter on soil nematode communities in three artificial stands in subtropical south China

Root exudates and litter inputs provide basic resources for soil food web. However, the effects of tree roots and litter on soil nematode communities in plantations with different tree species combination are still unclear. In September 2019, three artificial stands, e. g., Erythrophleum fordii Oliv. monospecific-planted forest, Pinus massoniana Lamb. monospecific-planted forest, and Erythrophleum fordii Oliv. and Pinus massoniana Lamb. mixed-species-planted forest, were selected to conduct a field manipulative experiment by removing roots and aboveground litter in Pingxiang, Guangxi Province. Soil nematode communities and soil properties were investigated in the plot of roots removal, litter removal, both roots and litter removal and corresponding control plots in March 2021. The results showed that roots removal altered nematode trophic group composition regardless the artificial stands by decreasing the relative abundance of fungivores and increasing the relative abundance of plant-parasites. Litter removal significantly decreased nematode total abundance, richness, nematode channel ratio and structure index, indicating that litter removal reduced the stability of soil food web. The results suggested that the input of tree roots, regardless artificial stands, was the main driving factor in shaping nematode trophic composition, and aboveground litter played an important role in maintaining the stability of soil food web. Furthermore, roots removal and litter removal had no significant impacts on soil nematode communities in E. fordii and P. massoniana mixed-species-planted forest, suggesting that the mixed forest with N-fixing tree species could facilitate the stability of soil food web compared to the pure conifer stand. Our findings highlight that introducing N-fixing tree species and mixing N-fixing species into pure conifer forests to enhance the plantation soil ecosystem stability.