Effects of resource manipulation on nematode community structure and metabolic footprints in an arable soil across time and depth

Abstract

Summary In an arable field the herbivore and detritivore soil food chains were manipulated by the following treatments: maize as crop, amendment with maize litter and bare soil, representing labile rhizodeposits, recalcitrant plant debris and soil organic matter as major resource, respectively. Samples from top soil, rooted zone and root-free zone were collected in two consecutive years. The impact of these differences in resource availability and quality on the nematode community composition, Maturity Index (MI), diversity () and metabolic footprints was assessed. Plant feeders were fostered by the presence of maize and fungal feeders by litter amendment. Correspondingly, non-parametric multidimensional scaling showed that nematode community structure was most different between plant and litter plots, while bare soil was nested in-between. This indicates that resource depletion under bare soil did not result in distinctly different nematode assemblages. The MI was low and similar across treatments and depths, reflecting soil disturbance by arable management. Nematode diversity was highest under the crop in the second year, which mirrors the general positive impact of plants on belowground processes. However, the composite footprint showed that the removal of plants from the system had an overall low impact on the metabolic response of the nematode community. Taken together, this indicates a considerable resilience of the soil food web to the disruption of both the root and detrital carbon channel over at least two vegetation periods.