Soil physicochemical properties shape distinct nematode communities in serpentine ecosystems

Abstract

Serpentine ecosystems have unique plant communities that have overcome the chemical and physical challenges presented by these soils. However, such a specific soil fauna community has not been identified. It is presumed that such communities are affected directly by the chemical and physical properties of serpentine soils. Here, we focused on nematodes, which comprise a ubiquitous and an abundant group in soil fauna, for comparing their community structure in serpentine and in non-serpentine soils based on morphological approaches. Root biomass, Mg, and Ni were higher in serpentine habitats than non-serpentine ones. In contrast, the soil water content, NO3− and Ca/Mg ratio were higher at non-serpentine habitats than serpentine ones. Among the nematode community indices, the channel index, which indicates the degree of fungal participation in the decomposition channels of soil food webs, was greater in serpentine (94.5 ± 4.8) than in non-serpentine (44.8 ± 3.2) habitats, whereas the enrichment index, which indicates the abundance and activity of primary detrital consumers, was greater in non-serpentine (56.2 ± 3.7) than in serpentine (40.2 ± 2.9) habitats. A non-metric multidimensional scaling scatterplot showed that nematode communities clustered into both serpentine and non-serpentine habitats by a permutational multivariate analysis of variance. Ca/Mg ratio accounted for the most variation in nematode communities: 90 % of the variation between the sites by envfit. Furthermore, relative frequencies of nine taxa (Filenchus, Malenchus, Mesodorylaimus, Monhystera, Paratylenchus, Plectus, Prodesmodora, Teratocephalus, and Tripyla) were greater in serpentine than in non-serpentine habitats, and those of five taxa (Alaimus, Bastiania, Cervidellus, Diptherophora, and Rhabditidae) were greater in non-serpentine than in serpentine ones by indicator species analysis. Although our study was a small sample size and unit, our findings suggest that the structure of nematode communities reflects the physicochemical properties of serpentine soils.