Effect of land use on soil nematode community composition and co-occurrence network relationship

Land use influences soil biota community composition and diversity,and then belowground ecosystem processes and functions.To characterize the effect of land use on soil biota,soil nematode communities in crop land,forest land and fallow land were investigated in six regions of northern China.Generic richness,diversity,abundance and biomass of soil nematodes was the lowest in crop land.The richness and diversity of soil nematodes were 28.8and 15.1%higher in fallow land than in crop land,respectively.No significant differences in soil nematode indices were found between forest land and fallow land,but their network keystone genera composition was different.Among the keystone genera,50%of forest land genera were omnivores-predators and 36%of fallow land genera were bacterivores.The proportion of fungivores in forest land was 20.8%lower than in fallow land.The network complexity and the stability were lower in crop land than forest land and fallow land.Soil pH,NH_(4)^(+)-N and NO_(3)^(–)-N were the major factors influencing the soil nematode community in crop land while soil organic carbon and moisture were the major factors in forest land.Soil nematode communities in crop land influenced by artificial management practices were more dependent on the soil environment than communities in forest land and fallow land.Land use induced soil environment variation and altered network relationships by influencing trophic group proportions among keystone nematode genera.

下辽河平原农田土壤线虫群落组成的季节变化

下辽河平原农田生态系统在管理过程中频繁的耕作、施肥以及农用化学品施用等引发了一系列问题,如土壤退化、耕地数量减少以及生产力下降等,不可避免地对土壤生物健康产生影响。为探究农田土壤人工管理对土壤生物群落动态的影响,本研究在辽宁沈阳农田生态系统国家野外科学观测研究站开展了农田土壤线虫群落组成的季节变化研究,对4个季节农田和废弃农田(对照)的土壤线虫群落组成、多度以及多样性等进行了比较分析。研究结果表明,土壤线虫总多度在废弃农田中显著高于农田,但季节间差异不显著。季节变化主要显著影响了自由生活线虫的多度,其在9月达到最高;季节变化也显著影响了属的数量,其在非生长季的11月最低。与废弃农田相比,农田管理显著降低了杂食捕食线虫和食真菌线虫的多度,土壤食物网结构相对稳定;而废弃的农田更易受到季节波动的影响,土壤食物网也受到一定的干扰。