Abstract
Grazing is a key driver of plant communities and soil functions in grassland ecosystems. Soil nematodes play a vital role in soil ecological functions. The aim of this study was to explore how grazing shapes soil nematode community in different soil layers. We investigated the composition, abundance, diversity, metabolic footprint, and food web metrics of soil nematodes over a gradient of grazing in the 0–10 cm and 10–20 cm soil layers in a meadow steppe. The relationships between nematode community structure and biotic and abiotic factors were analyzed by principal component analysis and structural equation model analysis. Light grazing increased the abundance of total soil nematodes by 18.5%. Intensive grazing decreased the carbon used in production and metabolic footprints of plant parasites, fungivores, and total soil nematodes in 0–10 cm soils. There was no difference in the carbon used in production and metabolic footprints of soil nematodes among different grazing intensities in the 10–20 cm soil layer. Soil moisture, aboveground biomass, belowground biomass and Shannon diversity of grass contributed more to changes in soil nematode composition in both soil layers. In the 0–10 cm soil layer, grazing directly and indirectly affected soil nematode diversity via soil moisture and aboveground biomass, while grazing directly affected soil nematode diversity in 10–20 cm soil layer. Our results indicate that increasing soil depth can weaken the effect of grazing intensities on soil nematode fauna. Grazing affected the soil nematode community structure via different paths in different soil layers.
Highlights
Grasslands are important ecosystems and occupy approximately one-fifth of the land surface in the world (Cao et al 2019)
Our results indicate that soil depth can weaken the effect of grazing intensities on soil nematode fauna
The abundance of bacterivores and omnivores/predators was not affected by grazing compared to G0, but G3 decreased the abundance of bacterivores, and both G3 and G2 decreased the abundance of omnivores/predators compared to G1
Summary
Grasslands are important ecosystems and occupy approximately one-fifth of the land surface in the world (Cao et al 2019) They assume crucial importance in maintaining biodiversity and combating desertification (Li et al 2020). It is well known that herbivore grazing can influence the structure and composition of aboveground ecosystems and can induce potential consequences in belowground ecosystems (Bardgett et al 1998), such as C and N allocation to roots (Hokka et al 2004; Ilmarinen et al 2005); faeces of herbivores can change, affecting the community structure and diversity of soil biota (Bardgett et al 1998; Wardle et al 2004). Herbivore grazing affects the soil fauna by decreasing or increasing the nutritional quality and quantity of plants or by nutrient return from animal wastes, but these nutrients have a heterogeneous spatial distribution (Wang et al 2006). We know little about the response of soil fauna to grazing in different soil layers
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