Figure 1.
Possible mechanisms driving a positive plant diversity-ecosystem process relationship.
The consumer-related ecosystem processes studied here are herbivory and decomposition. Based on existing literature we hypothesize different mechanisms driving the positive relationship between plant diversity and herbivory/decomposition, represented here by the different arrows. For details on the hypotheses see Introduction. Solid lines indicate expected positive correlations, dotted lines expected negative correlations. M1-3 = Mechanisms 1-3, DM = Dietary Mixing, MIH = More Individuals Hypothesis, PH = Productivity Hypothesis, RCH = Resource Concentration Hypothesis, RHH = Resource Heterogeneity Hypothesis. M1-3 are “unnamed” mechanisms, which are reported in the literature.
Figure 2.
Path diagram explaining plant community effects on decomposition and herbivory.
Models relate plant community variables (diversity, quantity and quality), species richness and abundance of (a) decomposer arthropods to decomposition, and (b) herbivorous insects to herbivory. Standardised path coefficients are given on top of the path arrows with significances indicated by *, P<0.05; **, P<0.01; ***, P<0.001. Non-significant paths are given in grey.
Figure 3.
Pairwise correlations visualizing the significant links detected in the path analysis relating plants, decomposers and decomposition.
We show the relationships between aboveground plant biomass and decomposer abundances (a), between decomposer abundances and their species richness (b) and decomposer species richness and decomposition (c). For statistics, see Table S2.
Figure 4.
Pairwise correlations visualizing the significant links detected in the path analysis relating plants, herbivores and herbivory.
We show the relationships between plant C:N ratio and herbivore abundance (a), herbivore species richness and their abundance (b), and between herbivore abundance and herbivory rate (c). For statistics, see Table S4.