Changes in soil nematodes in rhizosphere and non-rhizosphere soils following combined elevated [CO2] and canopy warming in a winter wheat field

Abstract

Soil nematode community is an important component of the soil food web, which has been widely recognized as a key bio-indicator for assessing the influence of climate changes on ecological functions. Climate changes have experienced evident increases in the atmospheric CO2 concentration [CO2] and temperature in the past decades. However, the effects of elevated [CO2] and warming on the abundance, diversity and function of soil nematode community remain unclear. In this study, the soil nematode communities in rhizosphere and non-rhizosphere soil were investigated under factorial combinations of elevated [CO2] (500 ppm) and canopy warming (+2°C) in a winter wheat field. The results showed that canopy warming significantly increased the nematode abundance by 31.3% but decreased its diversity by 14.5%, while elevated [CO2] showed no effect on the nematode abundance whereas significantly increased its diversity by 6.4%. The nematode diversity and genera richness decreased in the rhizosphere soil under combined treatment, indicating that canopy warming negated the positive effect of elevated [CO2] on nematode diversity. Meanwhile, canopy warming alone significantly increased the plant parasite index of nematode trophic communities in rhizosphere soil rather than in non-rhizosphere soil. Overall, the effects of climate changes on soil nematode community are greater in rhizosphere than non-rhizosphere soil, potentially affecting ecosystem functions in agricultural soil, and thus challenging the ecosystem health and food production in the future.