Soil nematode community composition and stability under different nitrogen additions in a semiarid grassland

Abstract

Anthropogenic input of reactive nitrogen (N) is an environmental problem that threatens the diversity and stability of belowground ecosystems. Soil nematodes are abundant in soil and are occurring at multiple trophic levels in the soil food web. However, how N deposition affects the composition and stability of soil nematode community is largely unknown. Here, we investigated the response of soil nematode community composition to N deposition at different sampling seasons and also estimated the stability of nematode community in a semiarid grassland in northern China. We found that the addition of N not only reduced the diversity of the nematode community, but also reduced the temporal stability of nematode community. The stability of different nematode trophic groups had different responses to N addition, and the community of plant parasites was more stable than the other trophic groups at a relatively higher N addition level. Moreover, soil pH was closely correlated with the stability of bacterivores, fungivores and predators-omnivores and the diversity of nematode community under different N additions. Our results highlight that N additions indirectly influence the synchrony and the stability of nematode community through change in soil nematode abundance and richness, and the variations of nematode community stability under different N additions are closely related to soil pH. These changes in nematode community composition and stability will eventually influence soil ecosystem function and nutrient cycling through biotic interactions in the soil food web.