Predicting the structure of soil communities from plant community taxonomy, phylogeny, and traits

Abstract

There are numerous ways in which plants can influence the composition of soil communities. However, it remains unclear whether information on plant community attributes, including taxonomic, phylogenetic, or trait-based composition, can be used to predict the structure of soil communities. We tested, in both monocultures and field-grown mixed temperate grassland communities, whether plant attributes predict soil communities including taxonomic groups from across the tree of life (fungi, bacteria, protists, and metazoa). The composition of all soil community groups was affected by plant species identity, both in monocultures and in mixed communities. Moreover, plant community composition predicted additional variation in soil community composition beyond what could be predicted from soil abiotic characteristics. In addition, analysis of the field aboveground plant community composition and the composition of plant roots suggests that plant community attributes are better predictors of soil communities than root distributions. However, neither plant phylogeny nor plant traits were strong predictors of soil communities in either experiment. Our results demonstrate that grassland plant species form specific associations with soil community members and that information on plant species distributions can improve predictions of soil community composition. These results indicate that specific associations between plant species and complex soil communities are key determinants of biodiversity patterns in grassland soils.

Fig. 1

The effects of plant species identity on the composition of soil communities from mesocosms containing monocultures. Boxplots represent pairwise Bray–Curtis dissimilarities in community composition between vs. within soils from the same plant species (a). Hierarchical clustering diagrams based on mean dissimilarities across the plant species (b). Bipartite network diagram, where edges (lines) connect plant species (green circles) to fungal taxa (red points) that occurred in the same mesocosm (c). The composition of cosmopolitan soil taxa (those taxa associated with all plant species), intermediate (taxa associated with only 2 to 20 plant species), and specialized (taxa that associate with only a single plant species) (d). The composition of functional groups of fungal taxa identified as being cosmopolitan, intermediate, and specialized across plant species (e)

Fig. 2

Relationships between plant species’ relatedness and differences in the composition of soil communities. Panel a shows a plant phylogenetic tree with species names colored by family (key shown in Fig. 1) with the corresponding heatmap showing the dissimilarities in the composition of each soil community. Colors represent the first principal coordinate analysis axis calculated from Bray–Curtis dissimilarities (a). The relationship between differences in the composition of soil communities and plant trait distances (b). Euclidean trait distances were calculated using all the traits shown in panel c. The relationship between differences in the composition of soil communities and individual plant traits (c). Points represent Spearman correlation coefficients (rho) and Mantel test results (P-value)

Fig. 3

Soil community composition is related to plant community composition in the field. Variation in plant community composition across the field samples ordered by the first principal coordinate score (i.e. the x-axis represents a gradient of plant community compositions where communities further apart are more dissimilar), and relationships between soil taxonomic group relative abundance and the plant first principal coordinate score (a). Linear trend lines were only plotted for groups that had a Pearson correlation P ≤ 0.05. Relationship strength between dissimilarities in soil communities and dissimilarities in plant communities (*P < 0.05, **P < 0.01, ***P = 0.001; Mantel tests; b). Pairwise Bray–Curtis dissimilarities in plant community composition, as assessed using aboveground tissue, are not related to dissimilarities in plant community composition as assessed using root tissue, but they are related to dissimilarities in plant community composition as assessed using plant DNA in soil (c)